Inches, feet, yards, miles
In what is called the English, or customary, system of measurement,
there are 12 inches in a foot, 3 feet in a yard, 16£ feet in a rod, and
5,280 feet in a mile. Why such odd numbers? Well, it’s because, over the
centuries, England was conquered by Romans, Saxons, and other groups of
people.
The Romans had a unit called a pes, or foot, that was a little shorter
than a modern foot. They divided the pes into twelve parts. Each part
was called an uncia, a word that means “a twelfth.” As you may have
guessed, it’s from the word uncia that we get the word inch. The
Romans also had a unit called a milia passuum, meaning “a thousand
paces.” As you may also have guessed, our word mile comes from
milia.
The Saxon invaders had a unit called a fdt, or foot, that was a little
longer than a modern foot. They divided their fdt into twelve equal
parts called thumas, or thumbs.
These were only a few of the units of length used in England until about
seven hundred years ago. Then, King Edward I decided that there should
be one standard of length for the entire country.
The king said that three grains of barley would make one inch, twelve
inches would make a foot, and that three feet would make an ulna, or
what we now call a yard. The standard for this new unit of length was an
iron bar thirty-six inches long.
Under this law, the new foot was a little longer than the Roman pes
and a little shorter than the Saxon fdt. And this led to a problem.
Land was measured in Saxon units. One of these was the rod, equal to 15
Saxon feet. The king didn’t dare to change land measurements, so he made
the rod equal to 16\| new feet, or the same length as 15 Saxon feet.
This meant that the farmers’ fields would be the size they had always
been.
About four hundred years ago, the queen of England, Elizabeth I, changed
the number of feet in the mile. This was done to bring the mile into
line with the rod, furlong, and other land measurements. The mile at
that time was 4,800 Saxon feet. Well, 4,800 Saxon feet is the same
distance as 5,280 modern feet. And that’s why the mile is now 5,280 feet
long.
So we have twelve inches in a foot because the Romans had twelve units
in their foot. And we have 5,280 feet in a mile because a king did not
dare to change the actual length of a rod.
