Laws of Cricket 1947 Code (Fourth Edition) - Law 5
The Ball shall weigh not less than 5 1/2 ounces, nor more than 5 3/4 ounces. It shall measure not less than 8 13/16 inches, nor more than 9 inches in circumference. Subject to agreement to the contrary, either captain may demand a new ball at the start of each innings. In the event of a ball being lost or becoming unfit for play, the umpires shall allow another ball to be taken into use. They shall inform the batsmen whenever a ball is to be changed.
Notes on Law 5
1. All cricket balls used in first-class matches should be approved before the start of a match by the umpires and captains.
2. In first-class matches, the captain of the fielding side may demand a new ball after the prescribed number of overs has been bowled with the old one. The governing body for cricket in the country concerned, shall decide the number of overs applicable in that country, which shall be not less than 75 overs, nor more than 85 overs (55 to 65 eight-ball overs). In other grades of cricket these regulations will not apply unless agreed before the toss for innings.
3. Any ball substituted for one lost or becoming unfit for play should have had similar wear or use as that of the one discarded.
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