Hands, a way of measurment

A hand is four inches. A horse under 14.2 hands is a pony. Any thing over 14.2 hands is a horse. I have no idea how they measure a horse. Maybe it's like how we measure people. I can just imagine some one saying to a horse, "Go stand against the wall. Stand up straight," Impossible. They have measuring devices. If a horse is 16.1 hands it is from the hoof to the whithers. Or shoulder.