Four and a quarter inches

Clause 5.7 of the Laws is a list of numbers. The blade may be no more than 4.25 inches wide, 2.64 inches deep, and 1.56 inches at the edges. The whole bat, handle inserted, may be no more than 38 inches long. The handle may be no more than 52 per cent of that length. Two coverings are limited: the material on the blade to 0.04 of an inch, the protection on the toe to 0.12.

Every figure is also given in metric, and the metric figures are conversions rather than round numbers: 10.8 centimetres, not 11. 6.7, not 7. 96.52 for the length. The Law converts, and rounds the conversions to a millimetre, except the length, which it gives to a hundredth.

The arithmetic is plain. 4.25 inches is 10.795 centimetres and the Law says 10.8. 38 inches is 96.52 exactly and the Law says so. Nobody chose 10.8 as a number to aim at. It is 4.25 in other units, and the inch figure is the one that was decided.

Width

4.25 inches, 10.8 centimetres, is the width of the blade. It is the number most people know if they know one, and in the text it is one entry among several, with no more weight than the others.

Depth and edge

2.64 inches of depth, 1.56 at the edges. These two numbers describe the blade in cross-section: how thick it may be at the spine and how thick at the sides. The difference between them, just over an inch, is the room the Law leaves for the curve from one to the other.

Between them they fix how much wood a blade can carry. Width alone does not do that; a bat can be four and a quarter inches wide and as thin as a plank. Depth and edge are what make the number mean something in the hand.

Length and the handle

38 inches overall, "when the lower portion of the handle is inserted". The length is measured on the assembled bat, not on the blade and the handle as separate pieces, which is why the clause has to say where the handle is when the measuring is done.

The handle itself is limited as a proportion, 52 per cent of the overall length, which for a bat at the maximum is 19.76 inches. The clause applies to sizes larger than 6; smaller bats are outside it, which is the Law acknowledging that bats come in sizes at all.

The two thicknesses

0.04 of an inch for material covering the blade. 0.12 of an inch for protection on the toe. One millimetre and three millimetres. These are the smallest numbers in Law 5, and they exist because a covering is a way of adding to the blade without adding to the blade. The Law measures the wood and then measures what may be put on it.

What is not in the list

Weight. Clause 5.7 limits length, width, depth, edge, handle proportion and two thicknesses, and it does not limit weight. A bat may be as heavy as its dimensions allow, and the dimensions are what the Law controls.

That is a choice about what to measure. Depth and edge together fix how much wood a blade can hold, and weight follows from that and from the wood. The Law measures the shape and lets the mass be whatever the shape makes it.

Why numbers

A bat is checked with a gauge, not an argument. Each figure in 5.7 is a thing that can be held against the bat: a width, a depth, an edge, a length. The clause is written so that the answer to whether a bat is legal is yes or no, and not a matter of judgement.

Most of the Laws are not like that. Most of them turn on a word an umpire has to weigh: wilful, reasonable, normally, fair. Law 5.7 turns on a ruler, and it is one of the few places in the code where the text and the measurement are the same thing.

Law 5, The bat: MCC Laws of Cricket, 2017 Code →

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No. 5 in By the Book, a series of 17.

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