History of Metrology

Background

Since humans began to use tools to perform simple production labor, they have been measuring. Initially, there were no measurement units or measuring tools. The object to be measured was simply compared with a part of the body, such as the distance between fingers or the length of hands stretched out to measure the length of an object, and a handful or a handful to measure the volume and capacity. Later, due to the development of production and exchange, measurement units and measuring tools appeared.

As early as more than 4,000 years ago, there were physical objects to represent measurement units. For example, the earliest length measurement unit in ancient Egypt, the cubit, was based on the length from the elbow to the fingertips. In the 10th century, the King of England set the length between his thumb joints as one inch and the length of his foot as one foot. To this day, "foot" and "foot" are the same word in English (foot). The

measurement units in ancient China were also taken from natural objects. As early as more than 2,000 years BC, the width of a millet was used as one fen, ten as one inch, and one hundredth as one foot. Books from the Han Dynasty (such as Confucius's Analects) record that "a finger can tell an inch, a hand can tell a foot, and an elbow can tell a fathom", indicating that in ancient times, the length of the top section of a finger was defined as one inch, the length of the thumb and middle finger (i.e., one cubit) was defined as one foot, and the length of two arms stretched out was defined as eight feet as one fathom. (According to research, one foot in the Zhou Dynasty was about 20 centimeters long, roughly equivalent to the length of a cubit)

In terms of measuring time, humans initially provided humans with a standard for measuring time based on some long-term repeated changes in nature, especially the rising and setting of the sun and the waxing and waning of the moon, and gradually formed the concepts of day, month, and year. Around 2000 BC, ancient Egypt invented the solar calendar based on the intervals between the appearances of Sirius, dividing each year into three seasons, a total of 12 months, 30 days per month, and 5 festivals at the end of the year, a total of 365 days. In the early 2000 BC, the ancient Babylonians had measured the duration of the moon to be 29 days, 12 hours, 44 minutes, and 3 seconds, which was only 1/3 second different from the data measured by modern astronomy. They developed a lunar calendar based on the waxing and waning of the moon, with each month being set at 29 or 30 days.

Since the ancient measurement units were determined based on natural objects, it was not rational, and the measurement systems in different countries were different, which caused great inconvenience and difficulties in communication. As early as the 17th century, some French scientists proposed the idea of ​​reforming and unifying the measurement system. In 1791, the French Congress adopted the proposal of the Academy of Sciences and took one forty millionth of the earth's meridian passing through Paris as the basic unit of length, which was called the meter. In 1792, French scientists made a precise measurement of the length of the earth's meridian between Dunkirk and Barcelona, ​​Spain. After all the measurement work was completed in 1799, the standard prototypes of meters and kilograms were made.

Although the metric system is more advanced than various measurement systems in history, it was later discovered that the length defined by the meter was mismeasured. Moreover, with the development of science and technology, some measurement units derived from the metric system lacked scientific connections with each other, which brought a lot of trouble to science and production. At the same time, some countries still use their own measurement systems, which seriously hinders international communication. In 1948, the 9th International Conference on Weights and Measures proposed to create a simple and scientific practical unit system that can be adopted by all signatories of the Meter Convention. In 1960, the 11th International Conference on Weights and Measures decided to name this unit system "International System of Units", with the international symbol SI, and to define prefixes, derived units and auxiliary units. In 1971, the 14th International Conference on Weights and Measures made further revisions, using seven units as basic units: meter, kilogram, second, ampere, kelvin, mole and candela. Each unit is given a strict theoretical definition, and the derived units are defined by the basic units through the selected equations, so that the units are reasonably linked to each other. In

1959, the State Council of China issued the "Order on the Unification of the Measurement System", which determined that the metric system would be the basic measurement system of China, and that the city system that people were accustomed to in daily life could be retained. It also announced the "Scheme for the Unification of the Chinese Names of Metric Measurement Units". After the creation of the International System of Units, the national metrology department actively prepared for the implementation work. In 1977, the State Council promulgated the "Regulations of the People's Republic of China on Metrology Management (Trial Implementation)", Article 3 of which stipulates: "The basic measurement system of our country is the metric system, which will gradually adopt the international system of units. The city system currently retained should be gradually reformed." In 1978, the International System of Units Promotion Committee was established to promote the international system of units. In 1984, the State Council issued the "Order on the Unified Implementation of Legal Measurement Units in China", requiring the country to basically complete the transition to legal measurement units by the end of the 1980s, allowing the city system to be used until the end of 1990, and from New Year's Day 1991, it is generally not allowed to use illegal measurement units.

Measurements before BC

3000 BC

The first city-state was established in the Middle East. The Sumerians used weights and measures in transactions. They were based on ancient Hebrew gold coins, which were about 8.36 g (129 grains or 0.29 ounces).

2575 BC

Pyramid (Cheops)

2575 BC

The standard of length preserved, the length of the legs of the Gudea statue is feet, he was the chief executive of the city of Lagash 4000 years ago. It was divided into 16 sections, 26.45 cm long (10.41 in long).

Egyptian builders had only simple plumb lines, wooden squares and rulers, but they measured to within millimeters. The dimensions of the Gizeh pyramid, completed by thousands of workers, boasted that the edges varied by no more than 0.05% of the average length - that is, only 4.5 inches over a span of 755 feet.

The ancients developed robust and accurate methods for measuring four quantities: length, area, volume and weight or mass, which they did not subdivide.

They used time to measure large lengths and areas. For example, a journey that took many hours or the moon. The amount of land plowed by a herd of oxen in a day was called an acre, and the length of a furrow was called a wave. Many ancient measurements originated from parts of the body or from readily available materials. We now talk about feet and the width of a hand when measuring length. Other measurements based on parts of the body are less obvious. The inch was once based on the length of the last joint of the thumb. A fathom is the distance between the tips of the middle fingers of both hands at arm's length, and a yard is the distance from the tip of the nose to the tips of the fingers of the right hand at

arm's length. The problem with using these as measurements is that everyone's body varies in size. An early method to overcome this problem was to define length according to some standard, for example, from the tip of the king's nose to the tips of his fingers at arm's length. The earliest preserved standard of length is the length of the legs of a statue of Gudea, the governor of Lagash about 4,000 years ago.

2600 BC

The first form of the sundial appears in China.

2500 BC

Moenjo-Daro, considered the first "city" located 300 kilometers north of present-day Karachi, Pakistan.

Excavations of measuring instruments from Moenjo-Daro demonstrate the importance of precision and accuracy. Weights, usually expressed in black silica, a hard, flint-like rock, were cut to exacting standards. Although the scale was somewhat broken, it was precisely spaced to .264 inches.

Stone goose weight standard, found in Mesopotamia. Weights were often measured in terms of products, such as grains, as a comparison. Because these weights could vary, standard systems of weights were invented. Early weight standards were of amazing accuracy, and stone weight standards in the shape of sleeping geese have been excavated.

1950 BC

The earliest known standard of length is a heavy copper bar excavated from Nippur on the Euphrates River. The bar was divided into 4 large sections, each of which was divided into 16 smaller sections, much like feet and inches.

448-432 BC

Parthenon, Acropolis of Athens

214 BC

China began to build the Great Wall

80-72 BC

The Coliseum was built in Rome

Measurements after AD

Egyptian measurement

Fingers Width of one finger
Palm 4 fingers
Hand 5 fingers
Elbow Length from elbow to finger
28 fingers wide, 20.6 in

Roman measurement

Foot The length of a foot was divided into 12 parts, called inches
Steps of 5 feet, 1000 of which became the Roman li

In the ancient system of measuring time, the day and night were divided into 12 hours each. This was convenient for using a sundial, and the Chinese used a similar method in an ancient way in 2600 BC. Because the light and darkness of the sun varied with the seasons, the length of the Chinese hour also varied. When water clocks began to be used about a thousand years after the sundial, the contradiction between the two measurement methods became obvious.

The working of the water clock was based on the fact that water flowed from one container through a small hole at a steady rate to another container. The amount of water in the other container was indicated by some kind of ruler - in the simplest way, marking the surface of the water. As the water surface moved, the time was shown to pass in hours. As the length of the hour varied with the seasons, a different water clock was needed for each month. The ancients solved this problem in various ways, such as having different face standards for each month. In that case, the water clock was kept in line with the sundial, which was still in use at the time. Later, the method of adjusting the water clock with the seasons was abandoned, and the sundial was used to show the same length of hours throughout the year.

In the 8th century, the Chinese began to equip water clocks with balance wheels. The balance wheel is a ratchet that allows a wheel to move only a certain distance and then stop. The continuous motion is replaced by a discrete "ticking" sound. Starting in the 14th century, the concept of the balance wheel was applied in Europe and was used to slow down the movement using weights suspended by thin ropes or chains. The movement was converted to the movement of the clock hands through gears. Mechanical clocks using balance wheels and weights improved performance and were placed in towers throughout Europe.

1215 AD

King John was forced by the English nobles to sign the Charter of Intent. Among other provisions, a standard measurement system was introduced.

1350 AD

King Edward I of England decreed that three grains of barley, full and dry, connected end to end, represented one inch. This ambiguous "standard" was still in effect hundreds of years later until the 19th century.

1590 AD

Dutch spectacle maker Hans Janssen and his son placed two lenses at the ends of a tube to examine tiny objects. This marked the creation of the first combined microscope.

1592 AD

Galileo placed a tube of gas into a container filled with colored liquids, creating the first primitive thermometer.

1602 AD

Richard More, a scholarly London carpenter, described a number of models of carpenters' rulers in a book in which he criticized the lack of standardization. [page]

1631 AD

Pierre Vernier introduced his invention for precision measurement, now known as the vernier ruler.

1637 AD

Hartford, CT Settlement, re-arranged each colony to follow a uniform plan so that a continuous standard could be established. Eight years later, as additional areas were added to the colony, the areas were re-evaluated so that they could be compared and equalized. A fine of 12 pence was established in 1647 for any goods sold without the standard approved by the town administrator. Town administrators need to make sure that the ruler used before signing is made of seasonal wood, and if it is broken or damaged, such as weight, yardage or measuring length, it will be considered defective.

1641 AD

British astronomer Mr. Gascoigne invented the cross wire, starting the transformation of the telescope from a simple observation device to a precision measuring instrument.

1648 AD

William Gascoigne first applied the spiral to a measuring instrument

1660 AD

Italy invented the alcohol thermometer

1670 AD

Mr. Gabriel Mouton, bishop of St. Paul's Church in Lyon, introduced a complete decimal weighing and measuring system, measuring for the first time physical prototypes as a reference rather than individuals. This decimal system is the basis of the metric system.

1683 AD

Dutch instrument maker Antony van Leeuwenhoek built the world's first high-performance precision microscope.

Before the 17th century, it was almost impossible to make precise measurements on anything. Although length and weight could be measured with a certain degree of accuracy, chemists had not yet realized the role of the balance, which was originally used by assayers. Time could only be measured in large intervals. Temperature and hydraulic pressure could not be measured at all.

Mr. Galileo changed all that. In 1581, when he was only 16, he discovered that the period of a pendulum is controlled only by its length. This discovery led to the commercialization of pendulum clocks at the end of the 17th century. In 1586, Mr. Galileo invented the principle of hydrostatic balance.

In 1600, he introduced the first instrument for measuring temperature. This was later adapted to become a workable thermometer, and was transformed into the modern thermometer by German physicist Gabriel Fahrenheit in 1714. It was Mr. Galileo who suggested Evangelista Torricelli to conduct research and invented the barometer. Mr. Galileo's invention of the telescope encouraged others to create cosmological telescopes, which led to the demand for differential screws, and the use of telescopes for research led to the widespread use of vernier, which was used to accurately measure angles.

1742 AD

Swedish astronomer Anders Celsius designed a thermometer that bore his name and was subsequently used as part of the metric system in many countries.

1775 AD

British inventor Jesse Ramsden invented the circular cutting machine. Ramsden's London workshop produced high-precision sextants, micrometers and balances. His precision theodolites were used for trigonometric surveys linking Britain to the European continent.

1780 AD

The Industrial Revolution begins.

The double caliper

leg measures the inside diameter, the upper part measures the outside diameter.

The double caliper

is a tool for cabinetmakers, and is used to measure the diameter of finished lathe products.

Logging calipers

An itinerant logging ruler maker, William Greenlief, designed a measuring device specifically for loggers. The wheel gauge measures the size of a log, with each turn being 5 feet. The caliper measures the diameter of a log in inches. The markings on the ruler indicate how much wood is obtained from a felled tree. The caliper defines the volume of a bent log in cubic feet.

The carriage

was used by blacksmiths to measure the edges of wood.

1791 AD

The metric system of measurement standards was proposed in France.

1792 AD

Jean-Babtiste Delambre and Pierre Mechain began measuring the arc of the meridian from Dunkirk to Barcelona, ​​leading to the establishment of a standard system of measurement.

1805 AD

The "Noble Minister" micrometer, with a resolution of 1/10,000 of an inch, was invented by Henry Maudslay.

1820 AD

The British Parliament passed the "Imperial Standard" for weights and measures, based on the yard and pound

. In the early 1670s, Jean Picard evaluated the length of the earth's meridians and proposed that measurements be based on meridians. That measurement, a unit of measurement called a meter, was one ten-millionth of the length from the pole to the equator. The basic unit of weight, called the gram, was also established. It was based on the weight of a certain volume of pure water at a given temperature.

Weights and measurements above and below the gram or meter were related to the decimal system.

Despite its own advantages, countries have been slow to abandon the traditional metric system of measurement. Even in France, where the system originated, the change was not made early. In 1875, the metric system was sufficiently established to lay the foundation for the creation of the International Bureau of Standards for Weights and Measures.

The International Bureau of Standards believed that scientific measurements could not be accurately made when lengths were based on the length of the earth and weights were based on pure water. Instead, the Bureau changed these measurements and used standard platinum-iridium bar lengths and standard platinum-iridium weights.

1848 AD

From the French patent, "un calibre ?vis et ?vernier circulaire" (outside micrometer)

uses a screw to propel tiny movements. Combined with a graduated scale, this principle became an accurate method for measuring tiny distances. Frenchman Jean Palmier was the first to put this concept into practice in 1848 with the screw gauge (later called the micrometer).

Square rulers made by blacksmiths in the 17th century, usually hand-forged tools. The blade and tongue were hammered at the joints, and the graduations were made by a measuring system developed by Joseph Whitworth at this time. In the original Whitworth workshop, the micrometer graduation scale represented one ten-thousandth of an inch. The screw had 20 threads in the imperial system, and the wheel was graduated in 500 parts. 500 times 20 gives a resolution of one ten-thousandth of an inch.

1867 AD

Davis Level. Adjustable bubble level, plumb bob and inclinometer patented in 1867, 1917

AD

Pneumatic Length Gauge developed for carpenters and fabricators

Measurement using an oscilloscope

Probably the most accurate way to measure is based on the interference of light waves. The principles involved are the same for water waves, light waves or sound waves. If the waves are identical, they can be adjusted so that they cancel or reinforce each other. If the waves are different, the superposition of each other will produce light and dark bands, called interference patterns. Measuring with interference patterns is called interferometry.

Among the first to apply the interference principle to measurement was Albert Michelson, in 1881. In 1887, he and Edward Morley used the principle to conduct one of the most famous experiments in the history of science. From their data, they determined that the speed of light was not affected by the motion of the Earth in space. This discovery helped to establish Einstein's theory of relativity, which includes the concept that the speed of light remains constant in a container.

Measurement in the computer age

Work in the 1970s and 1980s on the development of general-purpose computing systems made it possible to automate many measurement tasks and to analyze large amounts of dimensional data quickly. A notable example of the integration of computer technology with measurement is the Super COSMOS machine, located at the Royal Observatory in Edinburgh. It has a sophisticated Leitz coordinate measuring machine and a full-featured computer to collect dimensional and positioning data on a variety of objects.

Developments in software technology have also made it possible to measure complex shapes, such as gears, compressor rotors and complete automobiles, with extremely high accuracy. The analysis provides information to control the manufacturing process, which can significantly improve quality.

1923 AD

Interference comparator for measuring block gauges

1931 AD

The first electron microscope is invented by German physicist Ernst Ruska. Today, it is an important research device in laboratories and industry.

1935 AD

Electronic length measuring instrument with inductive probe introduced by Bauer

1957 AD

TESAMASTER outside micrometer

1963 AD

The world's first electronic measuring machine: "ALPHA", designed and manufactured by DEA.

1978 AD

Brown & Sharpe introduces digital vernier calipers.

1981 AD

The introduction of the MICRO-HITE height gauge.

21st century... Measurement in the computer age

The development of computers and software technology has made it possible to automate measurement tasks and quickly analyze large amounts of dimensional data. The development of software technology has also made it possible to measure complex shapes, such as gears, compressor rotors and complete vehicles, with extremely high accuracy. The analysis provides information for the manufacturing process, which significantly improves quality. (end)