Why is a football field called the gridiron?

A gridiron is a grated utensil on which food is broiled over a fire. Hence, figuratively, any network, as of pipes, railway tracks, etc., is called a gridiron. The term was applied to a football field because it is rectangular in shape and is traversed every five yards by white lines, which produce a gridiron effect. A gridiron dinner is not a dinner .cooked on a gridiron. Putting a person on the gridiron is to place him in an uncomfortable position; that is, broiling him over a fire as it were. The Gridiron Club, composed of a restricted number of Washington newspaper correspondents, adopted that name because at its dinners it caricatures and satirizes prominent public persons who are present. Grid is merely a shortened form of gridiron, which etymologically has nothing to do with iron, being a corruption of gredire, a variant of gredil, the source of griddle.