i dont know who first used the term but in geometry there are 360 degre in a circle then each degree is broken into 60 min each of 60 sec as the trig works out 1 min of a degree in angle at 100 yards is almost 1 inch and at 200 it would be 2 inch and so forth just as 2 min is two inches at 100 and 4 at 200 hope this helps
pat
