Length

Length is the most necessary measurement in everyday life. However, units of length in many countries still reflect human’s first methods of taking measurements.

Historians tell us that during the Greek and Roman empires, the inch was represented by the width of a man’s thumb. The foot has been used since ancient times and was measured by a man’s foot. The yard was created and used from a normal human step. The mile originates from the Roman word Mille Passus which means a 'thousand paces'. For the Romans, a pace was equal to two steps. This all could probably get confusing. But at the time, these measurements made it easy to explain how far away the next village was or to work out whether an object will get through a doorway.

Obviously, difficulties occur when you use measurements from body parts. The Egyptians thought of a solution and that was to create a “standard” measurement. This means that a specific measurement was chosen to be used throughout the country (for example the foot would be the same distance for everyone in the country. No more worrying about how big or small someone's foot was). A rod or bar, of an exact length, was kept in a central public place. From this 'standard' other identical rods can be copied and distributed through the community. Some countries kept their standards in temples which shows how precious it was to have these measurements. In Egypt and most other countries, when a length is standardized, it is usually the pharaoh or king's dimension which is taken as the norm. (So it would be the King’s foot length that the entire country would use).

Weight

For measurements of weight, the human body does not provide an easy approximation. It was found that grains of wheat were all pretty similar in size. Weight can be expressed with some degree of accuracy in terms of the number of grains - a measure still used by jewelers today.

Eventually, countries would take a piece of metal and weigh it against 10 grains of wheat. If the two balanced out, then everyone would know that piece of metal weighed 10 grains.

Volume

A reliable standard of volume is the hardest to achieve. Baskets, sacks, or pottery jars can be made to consistent sizes. Volume would show how much that basket can be filled. Therefore, people use to fill liquid into one specific jar to know how much of the liquid they had.

The Metric System

The metric system came in 1799, during the French Revolution in France. The existing system of measurement had become too chaotic and was temporarily replaced by a decimal system based on the gram and the meter. The metric system was to be, in the words of philosopher and mathematician Condorcet, "for all people for all time". The basic units were taken from the natural world (not like the body parts of ancient times). The unit of length called the meter was based on the dimensions of the Earth. The unit of mass called the gram was based on the weight of water that could fill a cubic millimeter. The units of measure were related to each other. These units of measurement were explained and instructions on how to use them were produced and distributed throughout France by the Academy of Science. By 1812, due to the unpopularity of the new metric system, France had reverted to a measurement system using units similar to those of their old system.

However, In 1837 the metric system was re-adopted by France, and also during the first half of the 19th century was adopted by the scientific community.

Until 1875, the French government-owned the meter and gram. In that year, control of these standards was giving to other countries so that they could use those measurements too. As more and more countries began to use the meter, it became even easier for scientists or people traveling to other countries. The measurements stayed consistent.