What is the historical significanceof
the barleycornin measurement?
The barleycorn (just a grain of barley)
definitely had a significant historical role
in determining the length of an inch and
the English foot (for more about the inch
and foot, see below). In addition, in tradi-
tional English law, the various pound
weights all referred to multiples of the
“grain”: A single barleycorn’s weight
equaled a grain, and multiples of a grain
were important in weight measurement.
Thus, some researchers believe the lowly
barleycorn was actually at the origin of
both weight and distance units in the
English system.
What were some early unitsused for
calculating length?
The earliest length measurements reach back into ancient time, and it is a convoluted
history. Some of the earliest measurements of length are the cubit, digit, inch, yard,
mile, furlong, and pace.One of the earliest recorded length units is the cubit.It was
invented by the Egyptians around 3000 BCEand was represented by the length of a
man’s arm from his elbow to his extended fingertips. Of course, not every person has
the same body proportions, so a cubit could be off by a few inches. This was something
the more precision-oriented Egyptians fixed by developing a standard royal cubit.
This was maintained on a black granite rod accessible to all, enabling the citizenry to
make their own measuring rods fit the royal standard.
The Egyptian cubit was not the only one. By 1700 BCEthe Babylonians had
changed the measurement of a cubit, making it slightly longer. In our measurement
standards today, the Egyptian cubit would be equal to 524 millimeters (20.63 inches),
and the Babylonian cubit (cubit II) would be equal to 530 millimeters (20.87 inches;
the metric unit millimeters is used here, as it is an easier way to see the difference
between these two cubits).
As the name implies, a digitwas measured by the width of a person’s middle finger
and was considered the smallest basic unit of length. The Egyptians divided the digit
into other units. For example, 28 digits equaled a cubit, four digits equaled a palm,
and five digits equaled a hand. They further divided three palms (or 12 digits) into a
small span, 14 digits (or a half cubit) into a large span, and 24 digits into a small cubit.
To get smaller measurements than a digit, the Egyptians used fractions. 43
MATHEMATICS THROUGHOUT HISTORY
Grains of barley, a common crop that was easy to
obtain, were a convenient but not very accurate
standard to use for measuring items in England
before better standards were developed. Taxi/
Getty Images.