Cricket ball
From Wikipedia, the free encyclopedia
A cricket ball is a hard, solid ball used to play cricket.
Contents |
[edit] Manufacture
Cricket balls are made from a core of cork, which is layered with tightly wound string, and covered by a leather case with a slightly raised sewn seam. The covering is constructed of four pieces of leather shaped similar to the peel of a quartered orange, but one hemisphere is rotated by 90 degrees with respect to the other. The "equator" of the ball is stitched with string to form the seam, with a total of six rows of stitches. The remaining two joins between the leather pieces are left unstitched.
For men's cricket, the ball must weigh between 5.5 and 5.75 ounces (155.9 and 163.0 g) and measure between 8 13/16 and 9 in (224 and 229 mm) in circumference. Balls used in women's and youth matches are slightly smaller.
Cricket balls are traditionally dyed red, and red balls are used in Test cricket and First-class cricket. White balls were introduced when one-day matches began being played at night under floodlights, as they are more visible at night. Professional one-day matches are now played with white balls, even when they are not played at night. Other colours have occasionally been experimented with, such as yellow and orange for improved night visibility, but the colouring process has so far rendered such balls unsuitable for professional play because they wear differently to standard balls. The white ball has been found to swing a lot more during the first half of the innings than the red ball. It also deteriorates faster than the red ball.
Cricket balls are expensive. As of 2007, the ball used in first class cricket in England has a recommended retail price of £70 (USD 140). [1] In test match cricket this ball is used for a minimum of 80 overs (theoretically five hours and twenty minutes of play). In professional one day cricket, at least two new balls are used for each match. Amateur cricketers often have to use old balls, or cheap substitutes, in which case the changes in the condition of the ball experienced during an innings in professional cricket, are not replicated.
[edit] Condition of a cricket ball
A new, highly polished ball is used at the start of each innings in a match. A cricket ball may not be replaced except under specific conditions described in the Laws of Cricket:
- If the ball becomes damaged or lost.
- If the condition of the ball is illegally modified by a player.
- In Test cricket, after 80 overs, the captain of the bowling side has the option to take a new ball.
- In One Day Internationals, there is a mandatory change of the ball at the start of the 35th over of each innings. The replacement will be a clean used ball, not a new ball. This rule was introduced in June 2007[2]
The ball is not replaced if it is hit into the crowd - the crowd must return it. If the ball is damaged, lost, or illegally modified, it will be replaced by a used ball in similar condition to the replaced ball. A new ball can only be used after the specified minimum number of overs have been bowled with the old one.
Because a single ball is used for an extended period of play, its surface wears down and becomes rough. The bowlers will polish it whenever they can - usually by rubbing it on their trousers, producing the characteristic red stain that can often be seen there. However, they will usually only polish one side of the ball, in order to create 'swing' as it travels through the air. They may apply natural substances (i.e. saliva or sweat) to the ball as they polish it, and some cricketers suck boiled sweets such as Murray Mints during a match to improve the polish their saliva can produce, but any other material is illegal.
The seam of a cricket ball can also be used to produce different trajectories through the air, with the technique known as swing bowling, or to produce sideways movement as it bounces off the pitch, with the technique known as seam bowling.
Since the condition of the cricket ball is crucial to the amount of movement through the air a bowler can produce, the laws governing what players may and may not do to the ball are specific and rigorously enforced. The umpires will inspect the ball frequently during a match. It is illegal for a player to:
- rub any substance apart from saliva or sweat onto the ball
- rub the ball on the ground
- scuff the ball with any rough object, including the fingernails
- pick at or lift the seam of the ball.
Despite these rules, it can be tempting for players to gain an advantage by breaking them. There have been a handful of incidents of so-called ball tampering at the highest levels of cricket, involving players such as Pakistani fast bowler Waqar Younis and former England captain Mike Atherton.
A new cricket ball is harder than a worn one, and is preferred by fast bowlers because of the speed and bounce of the ball as it bounces off the pitch. Older balls tend to spin more as the roughness grips the pitch more when the ball bounces, so spin bowlers prefer to use a worn ball. Uneven wear on older balls may also make reverse swing possible. A captain may delay the request for a new ball if he prefers to have his spin bowlers operating, but usually asks for the new ball soon after it becomes available.
Cricket balls are notoriously hard, and potentially lethal. Frederick, Prince of Wales, is often said to have died of complications after being hit by one, although in reality this is not true - although he was hit in the head by one, the cause of his death was a burst abscess in a lung. Glamorgan player, Roger Davis, was almost killed by one. Raman Lamba was killed when hit on the head while fielding at forward short leg in a club match in Bangladesh. Hence today's batsmen and close fielders often wear protective headgear. In a one-day international between England and Australia, England batsman Kevin Pietersen fractured a rib after getting hit there by a delivery from Australia's Glenn McGrath.
[edit] Cricket ball swing
The key to making a cricket ball swing is to cause a pressure difference between the two sides of the ball. The air pressure depends on the flow of air over each side of the ball. Swing is generated when bowlers, by accident or design, disrupt the flow of air over one side of the ball.
Normal swing is achieved by keeping one side of the ball polished smooth and shiny, and delivering the ball with the polished side forward, and the seam angled in the direction of desired swing. The outswinging delivery moves away from the right-handed batsman, while the inswinger moves in towards him. Normal swing is achieved by maintaining laminar boundary layer air-flow on the shiny side whilst creating turbulent flow on the seam side. These deliveries, particularly the outswinger, are the bread and butter of opening bowlers who get to use the ball while it is still new.
Reverse swing is very different from conventional swing. Although the seam is oriented in the same way as for an outswinger and the action is the same, the rough side of the ball is to the fore, and the ball moves in to the batsman like an inswinger. Reverse swing is achieved when the ball is bowled very fast. In this case the air flow will become turbulent on both sides before it reaches the seam.
[edit] Alternatives to cricket balls
Sometimes alternatives to a real cricket ball may be preferred for reasons of safety, practice, availability and cost. Examples include a tennis ball (most favoured) or a plastic version of the cricket ball, also known as an Incrediball.
Many casual players use a tennis ball wrapped in layers of some type of adhesive tape (often electrical insulating tape), which makes the relatively soft tennis ball harder and smoother. This is commonly referred to as a taped ball. A common variant is to tape only half the tennis ball, to provide two different sides and make it easy to bowl with prodigious amounts of silky swing.
[edit] Diamond cricket ball
The world's first diamond cricket ball was made in Sri Lanka with 2704 diamonds and 18 carat (75%) gold for the seam. The material used to keep the diamonds on the ball is similar to the one used on the wings of NASA space shuttles.[3]
[edit] See also
- Ball gauge
- Baseball (object) - ball as used in baseball
[edit] External links
