From HowStuffWorks.com
One problem that football players and officials have always had to deal with is exactly how to measure the 10 yards needed to gain a first down. First downs often decide games, but collegiate and professional football officials often measure them using a decidedly antiquated length of metal chain attached between two poles.
In my opinion, using the chains to accurately measure for a first down is the dumbest part of this uniquely American pasttime. Consider what typically transpires . . .
A team acquires possession of the ball through a variety of ways and the end result of that play is that the two game officials attempt to determine the EXACT location of the ball when the ball carrier was ‘down’. Consider that the ball may be very near to or touching the ground or could be 5 feet or more from the ground at the time the player is ‘down’. The officials have to make a JUDGEMENT call as to how far down field the ball may have traveled. They are probably several yards away from the ball carrier and perhaps behind or further down field from the ball carrier and may or may not have a clear view of the end of the play.
Then a measuring device is placed on the sideline by looking across the field and approximating the location of the ball had it been adjacent to the sideline. This device happens to be two poles with a 10 yard long chain between them. One pole is placed where the ball would be (based on JUDGEMENT), the chain is then stretched to it’s fullest length and the other pole is placed to indicate how far down field is 10 yards.
The offensive team has four plays to gain ten (10) yards towards the opposing end zone. On one of those plays the ball might get very close to that point. Once again at the end of the play the game officials are responsible for determine the exact position of the ball on the field when the ball carrier is ‘down’ from some distance away with all of the issues previously discussed. Another JUDGEMENT!
Suddenly the officials are dumbfounded. They can’t tell if the ball actually traveled 10 yards down field or perhaps slightly less. Now they must relay on that measuring device to make the JUDGEMENT call for them. I won’t go into detail about the process of accurately measuring the distance traveled and whether or not they were successfully. Understand that the process is intended to be highly accurate and is also frequently repeated to relocate the ball to the center of the field not giving advantage to either team.
So, step one we make a judgement call while players are moving at full speed at some distance away, then a judgement call from a minimum of 20 yards away. then another judgement call again at full speed and some distance away.
Then we pull out a chain and two poles to PRECISELY measure the distance traveled.
For gosh sakes, ditch the rule and use your judgement!