hrj

To expand on that a little further (as hrj expressed an interest in the physics of sports), crown green bowls is generally played in the north of the UK and the flat green version in the south. The jack (the smaller ball you bowl first and which you have to aim for) in crown green bowls is black, in the flat green version of the game, it's white. Also -- and here comes the physics! -- the bowls used for crown green bowls have a bias, that is they're weighted on one side so you can curve them around the slightly dome shaped green.