1911 Encyclopædia Britannica/Pace
PACE (through O. Fr. pas, from Lat. passus, step, properly the stretch of the leg in walking, from pandere, to stretch), one movement of the leg in walking; hence used of the amount of ground covered by each single movement, or generally of the speed at which anything moves. The word is also used of a measure of distance, taken from the position of one foot to that of the other in making a single " pace, " i.e. from 2 ft. (the military pace) to i yard. The Roman passus was reckoned from the position of the back foot at the beginning of the pace to the position of the same foot at the end of the movement, i.e. 5 Roman feet, 58-1 English inches, hence the Roman mile, }ni!le passus =1646 yards.
For pacing in horse-racing see Horse-racing.