Laws of Cricket 1947 Code (Fourth Edition) - Law 25
The ball shall be held to be "dead" - on being in the opinion of the Umpire finally settled in the hands of the Wicket-keeper or of the Bowler; or on reaching or pitching over the boundary; or, whether played or not, on lodging in the dress of either a Batsman or Umpire; or on the call of "Over" or "Time" by the Umpire; or on a Batsman being out from any cause; or on any penalty being awarded under Laws 21 or 44. The Umpire shall call "Dead Ball" should he decide to intervene under Law 46 in a case of unfair play or in the event of a serious injury to a player; or should he require to suspend play prior to the Striker receiving a delivery. The ball shall cease to be "Dead" on the Bowler starting his run or bowling action.
Notes on Law 25
1. Whether the ball is "finally settled" is a question of fact for the umpire alone to decide.
2. An umpire is justified in suspending play prior to the striker receiving a delivery in any of the following circumstances:
1. If satisfied that, for an adequate reason, the striker is not ready to receive the ball, and makes no attempt to play it.
2. If the bowler drops the ball accidentally before delivery, or if the ball does not leave his hand for any reason.
3. If one or both bails fall from the striker's wicket before he receives the delivery.
In such cases the ball is regarded as "Dead" from the time it last came into play.
3. A ball does not become "Dead" when it strikes an umpire (unless it lodges in his dress), when the wicket is broken or struck down (unless a batsman is out thereby), or when an unsuccessful appeal is made.
4. For the purpose of this and other Laws, the term "dress" includes the equipment and clothing of players and umpires as normally worn.
Reproduction of the Laws of Cricket is by kind permission of Marylebone Cricket Club