an intact seam, which produces greater conventional swing. But when a captain feels that a spin bowling attack is more likely to be successful, he will persist with the old ball, which is rougher and better grips the surface as well the bowler's fingers. In baseball the ball is replaced numerous times during a game to ensure it is in optimum condition. Various factors affecting the movement of a cricket ball: The aerodynamics of swing in cricket are different from baseball. Once a particular hemisphere of the cricket ball is more rough or scratched than the other, the fielding team meticulously works to preserve the shine on the other half by rubbing it on their clothes or by applying saliva (no "external" substances can be applied to alter the condition of the ball). Bowlers can then utilise both the asymmetrical aerodynamics of the surface combined with the effects the seam can have through the air to cause the ball to swing (curve through the air). Moreover, the raised seam also causes movement off the pitch in cricket, which is a very important part of medium pace bowling. The old ball in cricket also tends to generate greater amounts of reverse swing, which is swing towards the polished side. This can be exploited by genuinely fast bowlers (usually, those who can bowl over ). Especially on pitches in the Indian subcontinent, which tend to have abrasive surfaces, bowlers might resort to bowling across the seam as early as the tenth over, so as to quickly scruff up the ball and generate reverse swing early on. Strategies that rely on early reverse swing also need the backup of effective spin bowlers to be able to exploit the roughed up ball. Due to these factors, a batsman in cricket needs to watch very carefully how the bowler grips the ball even during his run-up, as well as the type of revolutions on the ball as it approaches. Master spin bowlers like Shane Warne and Muttiah Muralitharan, who were able to dramatically vary the trajectory, direction and extent of spin, frequently bowled deliveries with a scrambled seam to disguise the type of ball actually bowled. Batting first or last In cricket, since the strategies are greatly influenced by factors such as soil characteristics of the pitch, condition of the ball, time of the day, weather and atmospheric conditions, the decision to bat first or