By Tim Lambert
Measurement of Distance and Weight
People have always measured things. It was necessary to measure distances, and lengths and to weigh things. Today we take a measurement for granted but for our ancestors making exact measurements was difficult.
The earliest and most obvious way of measuring things was using parts of the human body. The length of a man’s foreman was called a cubit. The foot was the length of an average man’s foot. A fathom was the distance between the ends of a man’s outstretched arms. In England in the Middle Ages, an inch was three barleycorns laid end to end. According to legend in the 12th century King Henry I of England decreed that a yard was the distance from his nose to his outstretched thumb.
An acre was originally the amount of land a team of oxen could plow in one day. A furlong was a ‘furrow long’ in other words the distance oxen could pull a plow before they rested then turned around and started plowing the other way. A mile was a thousand double paces from the Latin word for a thousand, mille.
It is not known for certain how the gallon was invented but in the 18th century, there was an ale gallon and a wine gallon. In Britain in 1824 both were replaced by a new standard gallon. A quart is a quarter of a gallon and a pint is one-eighth of a gallon. A gill was a quarter of a pint.
Since Ancient Iraq people have also weighed things using balances. Today we use the abbreviation ‘lb’ for pound. It comes from the Latin word for balance, libra. Our word ounce comes from the Latin word for one-twelfth, uncia because in Rome a pound was divided into twelve units. In England, it was replaced by a system of measurement in which pounds are divided into 16 ounces. The word stone for measurement comes from the days when large stones were used to measure weight. The word ton is derived from tun, meaning a large cask for holding wine.
The anemometer, a device for measuring wind speed was invented in 1450 by Leon Battista Alberti.
People also invented ways of measuring temperature. In 1714 Gabriel Fahrenheit invented a scale for measuring temperature. On his scale 32 degrees Fahrenheit was the freezing point of water and 212 degrees Fahrenheit was its boiling point. In 1742 Anders Celsius invented a new method of measuring temperature. In 1848 Lord Kelvin invented the Kelvin scale in which zero degrees is absolute zero.
Following the French Revolution the metric system was devised but it only gradually replaced the old measurements in France. The metric system was made compulsory in France in 1840. It was made legal (but not compulsory) in the USA in 1866. The word gram comes from the French word gramme, meaning small weight. The word liter is derived from the litron, an old French measure of capacity.
In 1772 John Clais patented the first weighing device with a dial. In 1868 Alvin J Fellows patented a click spring tape measure.
Measurement of Time
People have also, of course always measured time. The phases of the Moon last approximately one month so it was easy for ancient people to measure that length of time. However, every society needs a length of time shorter than a month but longer than a day so the week was invented.
The earliest method of telling the time of day was the sundial. It is not known when the sundial was invented but it was certainly used in Ancient Egypt and Ancient Iraq. The Saxons used a candle clock. A candle was divided into segments and it took an hour for each segment to burn.
The mechanical clock was invented in the Middle Ages. Who made the first one and when is not known but it was around the end of the 13th century.
After photography was invented in the 19th-century people invented light meters to measure the intensity of light. The Geiger counter for measuring radiation was invented in 1928. Furthermore, the decibel scale for measuring sound was invented in 1929.
About 240 BC a Greek called Eratosthenes measured the circumference of the Earth. In 129 BC Hipparchus measured the distance to the Moon.
In space, distances are measured in light-years (the distance light travels in a year in a vacuum). But astronomers also measure distances in parsecs (1 parsec is 3.26 light-years). An astronomical unit is the mean distance from the Earth to the Sun (149,597,870,700 meters). At the opposite end of the scale, a micrometer is one-thousandth of a millimeter. A nanometer is one-thousandth of a micrometer.
Last revised 2023