The weights and measures used in ancient civilizations were carried to others through trade or conquest.
Thus, in the early Middle Ages, the units adopted were those of the Romans, the last and largest empire of antiquity, which carried them throughout Europe, western Asia, and Africa. No doubt the most used were still those of the human dimensions.
Obviously more precise measures were needed for certain activities, such as Byzantine and Arab constructions. These peoples certainly had their weight and measurement standards, although they were different for each region.
Apparently, no standard was created nationally until, in England, Richard I (reigned from 1189 to 1199 as early as the twelfth century) determined units for length and capacity. These were iron and maintained in various regions of the country by regional authorities in order to prove the veracity of a measure.
From this time date the yard and gallon, to this day used by the English-speaking countries. Several versions exist to explain the appearance of the yard: in northern Europe it is assumed that it was the size of the brace worn by the Anglo-Saxons and in the south would be twice the length of the Babylonians' ulna. Its value may also have been determined by Henry I (reigned from 1100 to 1135), who would have set its length to be the distance between your nose and the tip of your straight arm. Information like this is probably not really true, since most of the standards of the Middle Ages were actually created by sovereigns, first interested in measuring the values of their kingdoms.
The standard weights were those of the ancient peoples, according to the region, generally keeping the grain as a fundamental unit. In some European regions, the use of the "AV" system continued in commercial transactions. For the jewelry and gemstones trade, which required more delicate measurement processes, the "troy" system was used, whose units were:
- grain (gr.)
- pennyweight (dw.t)
- ounce (oz.t)
- pound (Ib.t)
For gemstones, unity was the carat, which is approximately 4 grains. Of all the standards of weights and measures created, none achieved an international and homogeneous use, and there are still remnants of antiquity. The situation became more delicate and confusing due to inaccurate reproduction, misinterpretation and dishonesty of some.
The same was not true of the measures of time that had already been standardized by Julius Caesar, and their calendar was adopted at least throughout Europe. We must also remember that in the inventions of the late Middle Ages and Renaissance cautious standards were adopted, as this was a new activity and could be very well controlled. As an example, typography and printing, whose movable types of international standards were created in the late 15th century and are still maintained today.
By the late eighteenth century, the diversification of measures was enormous, making commercial transactions very difficult. In France, the situation was worse, and thanks to the new ideas brought about by the French Revolution of 1789 and the impositions that brought about the flourishing of the industrial age, a commission of men of science was established for the determination and construction of standards, so that universal. Patterns should reproduce natural phenomena so as not to depend on future changes. After studies and research, the commission that included famous names like Borda, Lagrange and Laplace concluded that unit of length should belong to the decimal system, more easily, and attached to one of the following three natural phenomena:
- period pendulum length (2 oscillations) equal to 1 second, latitude 45 °
- 1/4 length of equatorial circle
- 1/4 length of terrestrial meridian from the equator to one of the poles
As in the first the measurement would depend on quantities outside the length, such as time and weight, and as measurements of the equator were almost impossible, the meridian proposition was accepted, because, besides not presenting the defects of the previous ones, it already had a good comparison. The meridian passing through Paris had already been measured precisely and could be compared with the new determination. Immediately the necessary measures were taken for the work and five committees were appointed for the execution, which included Lavoisier, Coulomb and Legendre. Due to the delay the venture would take and the urgency of setting up the system, the provisional meter based on the old measure was proposed and accepted by the Assembly. Later it turned out that the difference really was minimal.
The distance from the North Pole to Ecuador is almost 10,000,000 meters. The standard units were meter, kilogram and second. The meter was defined as the tenth millionth of the measured land meridian from Dunkerke to Barcelona. The unit of mass was the kilogram, made of iridised platinum, mass of approximately 1 liter of distilled water at 4 ° C. O second it was the unit of time, worth 86,400 of the average solar day. By decree law, the units became official in France, and within a few years several countries were already adopting them. The standards were made and exact copies were sent to countries that legalized the metric system, including Brazil.
Annually, around 1870, the members of the International Confederation of Weights and Measures and in 1875 the establishment of the International Bureau of Measures was determined. Thirty countries participated, among which Brazil, through its representative, Viscount de ltajubá. England decided not to adopt the decimal system, to this day maintaining its units together with the United States. With the scientific and technological development of our century, there was, besides better ways of defining the units, their insufficiency, since there was no standard for fundamental quantities as in the case of electricity.
Finally, in 1960, at the XI International Conference on Weights and Measures, the International System of Units was adopted and the meter and the second were redefined, as you found in this chapter. The fundamental quantities of SI are: Length, Mass, Time, Electrical Intensity, Temperature and Light Intensity.
Due to the serious damage that England suffers from not adopting the IS, she started to use it officially. As you may have observed, a scientific model or theory is never eternally accurate and may change as science and technology requires it as it develops.