It was natural for humans to use their own dimensions as a basis to measure distances. Thus arose the inch, the width of a thumb; the span, the width of the palm of the hand with spread fingers; the foot, the length of a human foot; the cubit, the distance from the elbow to the tip of the middle finger; the fathom, the distance between the two hands with outstretched arms; the pace, the distance between the two feet while walking; and so on.
This system of measurement has two problems. The first: that these lengths depend on each person. The second: that they are not simple multiples of one another. To solve the first problem, standard values were introduced. To solve the second problem, some of the measurements were slightly modified. Thus, in England, the inch was approximated by one-twelfth of a foot. This introduced a third problem, because each country chose different standard values and made approximations in its own way.



