Whereas today we have tools like this square footage calculator to keep measurements consistent, for most of human history there was little need for a system of standardized measurement. For example, if you are building your own home in a pre-industrial era, it only mattered that the measurements you use are consistent throughout the project; there is no need to deal with a standardized system of units.
In addition, in an age where trade was done via bartering, at markets and fairs, there may have been some very basic form of measurements (a bag of grain, for example) which could be exchanged for livestock or other products.
Ultimately, however, the transaction would have been between two individuals, and therefore required no overarching system of units.
Because travel was limited in the era before the railways, there was a variety of local measurements, varying from village to village or region to region. It was not until the industrial revolution that there was a push towards standardization.
As speedier travel became the norm, regional quirks in measurement were eliminated and central governments started to standardize what was meant by each unit. International trade and travel made this even more the case.
Today there remains only one major global divide when it comes to measurement – Metric and Imperial systems – and, perhaps, as the twenty-first century progresses, even this difference will diminish.
Then we will have a truly global system of weights and measures.
The Imperial System
The history of the imperial system goes back as long as humans have been measuring things. Units such as a ‘foot’ demonstrate that the system was based on an intuitive sense of how long objects are in relation to the human body.
The ‘cubit’ was used in Ancient Egypt and refers to the distance from a man’s elbow to the end of his middle finger.
The system that we now know as the ‘Imperial System’ came about under the auspices of the British Empire in the seventeenth century. Because the British Empire was the largest in the world, it was able to introduce a standardized system based on its own units of weight and measurement.
Many of these had been in place for centuries, and so the relationship between the units is often quirky, rather than intuitive.
The system remains relevant today because of its adoption in the United States, where it has remained.
While the rest of the world uses the metric system, the U.S. has remained loyal to the Imperial System, even after leaving the Empire it came from. Under the Imperial system, weight is measured in pounds.
Each pound is made up of 16 ounces (and an ounce is made up of 16 drams).
1 pound = 16 ounces
1 ounce = 16 drams
2,000 pounds makes a short ton, and 2,240 pounds makes a long ton.
2,000 pounds = 1 short ton
2,240 pounds = 1 long ton
For length, the standard unit is a mile. This can be divided up into eight furlongs, made up of 220 yards each (or 1760 yards in a mile).
1 mile = 1,760 yards
A yard is made up of 3 feet, and each foot is made up of 12 inches.
1 yard = 3 feet
1 foot = 12 inches
Within the Imperial System, there are more units and subunits based on historical rationale.
For example, a rod is 5 and 1/2 yards long, and a chain is 4 rods.
1 rod = 5.5 Yards
1 Chain = 4 rods
These have their roots in local traditions within the British Isles, and there are many similar examples across the Imperial System.
The Metric System
In the aftermath of the French Revolution, many of the old orthodoxies were being challenged.
After all, if you can execute your king and rebuild all the institutions of the state, surely you can decide whether a system of measurement is the most efficient.
As a result, in 1799, the French adopted what we now know as the ‘metric system.’ The system is designed to be standardized, with weights and measures all connected with one another, and designed to be broken down into intuitive subsections.
1 liter of water weighs 1 kg.
1 km = 1000 m
1 m = 100 cm
1 cm = 10 mm
One kilometer can be broken down into one thousand meters (m), which consists of 100 centimeters (cm), which are made up of 10 millimeters (mm).
Converting 1,500 millimeters into meters is, therefore, a far easier task than turning 31 and 1/2 inches into feet.
With the rise of Napoleon and his domination of Europe, the metric system spread throughout the continent and eventually to the rest of the world. Although Britain was a hold-out against Napoleon, it has adopted some parts of the metric system.
Road signs in Britain still give distances in miles, although many Brits (particularly younger ones) are more comfortable working in the metric system than the imperial system.
In 1875, the General Conference on Weights and Measures was the first major international attempt to standardize measurements on a global scale. It also updated measurement units and creates new ones as the need requires.
In 1960, the General Conference gave way to the International Committee on Weights and Measures, which introduced the System of International Units (sometimes abbreviated as SI).
This further standardized the metric system and created an international scientific standard.
As well as length and weight (meters and kilograms, respectively), SI units also include standardized values for electric current (ampere), light intensity (candela) and amount of a substance (mole).
In the fourteenth century, English king Edward II standardized the size of an inch to three grains of barley placed in a row. An inch had historically been the width of a man’s thumb, although this obviously left scope for discrepancies between thumbs of different sizes. The etymology of inch is the Latin unciae, which is the origin of both inch and ounce.
The yard as the standard unit of measurement in England was reintroduced by Elizabeth I in the sixteenth century after England had briefly used the ‘ell’ as a measurement (driven by a desire to ease trade with European cloth drapers).
In the eighteenth century, the British Parliament commissioned the creation of a ‘true yardstick,’ which was used as a means of measuring other yardsticks, and thereby creating a standardized length of a yard.
However, in 1834, a fire in Parliament led to the destruction of the yardstick, meaning that a new one was required. Over the next two decades, Parliament created 40 official yardsticks, which they sent out around the world to ensure a truly global standard. With the rise of the metric system, it became easier to define the length of a yard.
In 1959, an international treaty fixed the length of the yard at 0.9144 meters exactly.
Using lengths at home
When you are measuring lengths at home, you may be required to convert between metric and imperial. If you are working on a building project, whether that is installing new windows in your basement or putting in new flooring, precision is critical.
The following table will help with the most common conversions:
The origin of the 16 ounces to a pound system is complex, involving Sumerians, Arab traders, the Hanseatic League, and different – and competing – measurements between different industries.
Generally, however, the benefit of the 16-ounce system (known as the avoirdupois system) won out because of the ease of division. 16 ounces can be divided in half, fourths, eighths, or sixteenths with ease, meaning that it is easier to use it with smaller amounts.
Some practical considerations when measuring weight is that it is effectively a measure of force, or energy. That means that when you place a bathroom scale on a carpet, some of the force is absorbed by the carpet, meaning your weight will register as lower than it actually is.
As space exploration has developed, scientists have had to factor in the impact of different gravities on weight.
The Apollo XI mission used pounds and ounces in its calculations, although they were required to do calculations to ensure that Neil Armstrong and Buzz Aldrin were able to remain on the moon despite its lower gravity.
The imperial units of pints and gallons are one of the few remaining sets of units that differ between the U.S. and the U.K.
The reason for this is that the British updated their definition of a gallon in 1824, which the Americans declined to do – favoring instead the British wine gallon as defined in 1707.
This means that the U.S. pint (1/8 of a gallon) is 473 ml and the U.K. pint is 568 ml. A U.K. pint is 20 fluid ounces, whereas a U.S. pint is 16 fluid ounces,
1 pint = 473 ml = 16 oz.
1 pint = 568 ml = 20 oz.
meaning that the United States technically does not use the Imperial System when it comes to volume.
When factoring in the gallons of water in a water heater, for example, you need to be sure that you are using the correct measurement.
In general, volumes listed in the United States will follow the U.S. system, although if you are importing parts from elsewhere in the world, be sure that you have checked how ‘gallon’ is defined (ironically, the best way to do this is using the metric system!).
Like the 16 ounces in a pound, the reasoning behind the system of hours, minutes, and seconds is also based on simple math. The Babylonians regularly used base 60 in their numbers, because it can be divided by 2, 3, 4, 5, 6, 10, 12, 15, 20, or 30 leaving whole numbers.
The Babylonians gave us the modern system of measuring time, as well as the division of a circle up into 360 degrees.
Despite the efforts of the French Revolution and the Swiss company Swatch in 1998, there has never been a successful development of metric time.
The current system of measuring time is one of the few instances of a truly global standard – wherever you go in the world, a minute is one-sixtieth of an hour, and there are 24 hours in a day.
1 minute = 60 seconds
60 minutes = 1 hour
24 hours = 1 day
It’s perhaps because of the day is a fixed unit of time (despite the variance in the length of daylight and nighttime hours) that the time measurements we use are universal.
The history of pressure measurement is linked to the development of heat-measuring technology.
Since Galileo developed a tube to show changes in temperature by drawing water, scientists have demonstrated that pressure and temperature are intrinsically linked. In the seventeenth century, scientists created the first vacuum (an area of no pressure) and discovered the idea of air pressure (since Aristotle scientists had assumed that air had no weight).
Early experiments challenging Aristotle’s theories were led by Blaise Pascal and as a result, the SI unit of pressure is Pascals (Pa), which is measured in terms of Newtons (after Newton’s theories of force) per square meter.
In the Imperial System, pounds per square inch is the most common unit of measurement. Throughout our home and daily lives, we regularly measure pressure.
Whether it’s ensuring our car tires are fully inflated, or checking our boiler has enough pressure to adequately function, knowing and understanding pressure is critical.
Ultimately, whatever the systems of weights and measures in use in your country, there is a level of standardization that has existed for at least a century.
Unlike our ancestors, we can order parts for a building project from anywhere in the world, safe in the knowledge that there is a shared vernacular of units. Although the competition between the Metric and Imperial Systems continues, the ease of conversion between the two means that it presents few problems in daily life.
A quick Internet search or a calculation in your phone and you’ll be able to convert Metric to Imperial or vice versa. And that’s clearly an improvement from the days when each village and industry had its own system of weights and measures.
Sources and Further Reading