Pace. The length of a step in walking or marching, reckoned from the heel of one foot to the heel of the other; -- used as a unit in measuring distances; as, he advanced fifty paces. "The height of sixty pace ." --Chaucer. [1913 Webster]
Note: Ordinarily the pace is estimated at two and one half linear feet; but in measuring distances be stepping, the pace is extended to three feet (one yard) or to three and three tenths feet (one fifth of a rod). The regulation marching pace in the English and United States armies is thirty inches for quick time, and thirty-six inches for double time. The Roman pace (passus) was from the heel of one foot to the heel of the same foot when it next touched the ground, five Roman feet. [1913 Webster]
Roman pace (passus): 5 Roman feet. 58 inches (approx). Double step.
Geometric pace: 5 feet. 60 inches. Modern version of Roman pace.