Unit Definition (feet [international, U.S.])
The human foot has long been a standard unit for the measurement of length. Over history this size has varied from region to region and there is some discrepancy as to an exact standard or origin of the standard measurement for feet that we use today. In England, the Roman foot was replaced after the fall of Rome by the natural foot. The modern foot (1/3 yard or about 30.48 centimeters) did not appear until after the Norman conquest of 1066. It may be an innovation of Henry I, who reigned from 1100 to 1135. Later in the 1100's a foot of modern length, the "foot of St. Paul's," was inscribed on the base of a column of St. Paul's Church in London.

Unit Definition (sadzhen)
The sadzhen is a traditional Russian unit of distance corresponding roughly to the English fathom and French toise. Early in the 1700s, Czar Peter the Great fixed the length of the sadzhen at exactly 7 English feet. This equals 3 arshin or 2.1336 meters. Sagene is an older transliteration of the Russian word.