When I was younger and much more in shape I was a soccer (football) referee. On top of being great exercise and fun, there was the memorization of the 17 laws of the game. This blog post will focus on Law 2 - The Ball.
Law 2 states that the ball must be:
- made of leather or another suitable material
- have a circumference of not more than 70 cm and not less than 68cm
- At the start of the match it cannot weigh more than 450 g and not less than 410 g; and
- have a pressure of not more than 0.6 - 1.1 atmospheres.
Other considerations on Law 2 are that should the ball become defective during a match, the match will be restarted by a drop ball at the location where the original ball became defective. If it became defective at a penalty or kicks from the mark, the penalty will be retaken. If the ball becomes defective during a restart the ball is replaced and the game restarted accordingly. I have to say in my 16+ years as a referee I have never had to replace a defective ball, many that were lost on roads and highways, but none as a result of becoming defective during the game.
From a topical perspective there are plenty of stamps that have been issued with soccer balls appearing on them. Below are some more.