A football field is 330 feet long by 160 feet wide. At each end are goal posts set 18 feet 6 inches apart, with a crossbar 10 feet above the ground. The field is marked off in chalk lines similar to a tennis court, these lines being 5 yards apart. The centre of the field where the play starts is 55 yards from either end. It is usually customary to run lines parallel to the sides of the field, also 5 yards apart, but as a field is but 160 feet wide the first and last of these lines are but 5 feet from the side lines instead of 5 yards. The lines on a football field make a checkerboard effect and have given to the field the name of “gridiron.”

Football is a game where eleven men try to force the ball back of the opposing players’ goal line by various efforts in running with it or in kicking, while the opposing team meanwhile, by throwing the runner or by pushing him back, try to prevent any gain being made. Each team is allowed a certain number of attempts to make a certain distance and, if they fail to do this the ball becomes the property of the other team to make a similar attempt. Each of these attempts is called a “down,” and, according to the rules, after three attempts, if the runners have failed to gain the required distance, the ball is given to their opponents. In practice it is customary for a team to kick the ball on its last down and thus to surrender it just as far from its own goal line as possible. The distance that must be made in three downs according to the present rules is ten yards. Sometimes a team will not kick on its last down because the distance remaining to be gained is so little that the quarter-back feels sure that one of his men can make it, but this is an exception. When ten or more yards are gained the ball becomes at first down again and the team has three more attempts to make another ten yards figured from where the ball was finally downed.

The ultimate object of “rushing the ball,” as this play is called, is to place it on the ground behind the enemy’s goal line, which is called a “touchdown.” Sometimes a team will succeed in getting the ball almost over the goal line and then because of the superior resistance of its opponents will find that it can advance it no further. It is then customary for one of the players who has had practice in drop kicking to attempt to kick what is called a “goal from the field” or “field goal.” This play counts less than a touchdown in the score, counting but three points, while a touchdown counts five, but many a game has been won by a field goal.

Football scores between evenly matched teams who play scientifically are usually low, one or two scores in a game being all that are made. It frequently happens that neither side will score, but, unlike baseball, the game does not continue after the time limit has expired, but simply becomes a tie game. The game is divided into four periods of fifteen minutes each. There are resting periods of three minutes each between the first and second and third and fourth periods, and fifteen minutes between the second and third periods.

At the beginning of the game the two opposing captains toss up a coin and the winner of the toss has the choice of goals or of the ball. His decision will be governed by the position of the sun and the wind conditions, two very important things in football. After each score the sides change goals, however; so the choice is not so important unless the game happens to be scoreless.

At the first play the ball is placed in the centre of the field and is kicked off, a man on the opposing team trying to catch it and to run back as far as possible before he is tackled and the ball “downed.” The next lineup takes place at this point and the game proceeds until a score is made. After each score the ball is put in play just as at the beginning of the game.

The quarter-back calls out a series of numbers and letters called “signals” before the ball is put into play. These signals will tell his team what the play is to be, whether a run around end, a kick, or a mass play on centre, for example. The matter of thorough coaching in signals is very important and must be practised by the team until it can tell in an instant just what the play is to be when the play starts. The centre stoops low and holds the ball in an upright position on the ground between his feet. The quarter-back is directly behind him with outstretched hands ready to receive it. After the signal is given the team must be ready to execute the play, but must not by look or motion permit its opponents know what the play is to be. At a touch or word from the quarter-back, the full-back snaps the ball back and the play starts.

The position of the men on a team is generally as the diagram shows but for various plays other formations are used, provided that they do not violate the rules, which specify just how many men must be in the lineup and how many are permitted behind the line.

The first requirement of signals is to have them simple. In the heat and stress of a game the players will have but little time to figure out what the play is to be, even though it may all have seemed very simple on paper.

To begin a code of signals each position on the team is given a letter. The eleven positions will require eleven letters and no two must be alike. It would be possible of course to simply start with the letter “a” and go to “k,” but this system would be too simple and easily understood by your opponents. A better way is to take a word easily remembered in which no letter occurs twice, such as “B-l-a-c-k-h-o-r-s-e-x” or any other combination. “Buy and trade” “importance,” “formidable,” and many others are used. The same principle is used by tradesmen in putting private price marks on their goods.