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| Origins of Metrology | |
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The ancients developed moderately accurate ways to measure four quantities: length, area, volume, and weight or mass, which they did not distinguish.
They used time to measure large lengths and areas. For example, a journey was so many hours, days, or moons. An acre was the amount of land that a team of oxen could plow in a day, and the length of the furrow was called a furlong.Many ancient measures were derived from body parts or easily obtainable materials. We still speak of the foot and the hands when measuring length. Other measures based on body parts are less obvious. The inch was once based on the length of the last joint of the thumb. The fathom was the distance between the tips of the middle finger with the arms outstretched. The yard was the distance from the tip of the nose to the end of the fingers with the right arm outstretched.
The problem with these measures is that bodies differ in size. Early attempts to overcome this included defining the lengths in terms of some standard, the distance from the king's nose to the fingers of his outstretched arm, for example. The earliest preserved standard for length is the foot of a statue of Gudea, the governor of Lagash, a Mesopotamian city of about 4000 years ago.
2600 B.C.
Primitive forms of sundials used in China.
2500 B.C.
Moenjo-Daro, considered the first "city" located 300 miles north of today's Karachi in Pakistan Measuring devices unearthed from Moenjo-Daro testify to the importance placed upon precision and accuracy. The weights, generally made of chert, a hard flint-like rock, were cut according to strict standards apparently under the control of a central authority. The broken ruler shown is marked off at exact intervals of .264 inch.Stone Goose Weight, Mesopotamia. Weight was often measured by using produce, such as grain, for comparison. Since these weights can vary, standardized systems of weights were invented. Surprisingly accurate early weights from the region were made of stone and carved into the shape of sleeping geese.1950 B.C.
The first known standard measure of length was a heavy copper bar, unearthed at Nippur on the Euphrates River. It is marked with four large units, each divided into 16 smaller units, much like feet and inches.
448-432 B.C.
The Parthenon, Acropolis, Athens
214 B.C.
Great Wall Of China begun
80-72 B.C.
The Coliseum, Rome
Egyptian Measurements
A Digit = One finger width
B Palm = four digits
C Hand = five digits
D Cubit = Elbow to Fingertips
(= 28 digits, 20.6 in)Roman Measurements
E Foot length of one foot subdivided into 12 unciae, hence our inches
F Pace (= 5 feet), 1000 made up the Roman Mile
In ancient time-measurement systems, day and night were divided into 12 hours each. This was convenient for use with sundials, which the Chinese used in a primitive form as early as 2600 BC. Because the length of daylight and darkness varies with the season, so did the length of the Chinese hour. When water clocks came into use, about a thousand years after sundials, a conflict between the two forms of measurement was apparent.
A water clock works because water from one container flows through an opening at a steady rate into another container. The amount of water in the other container moves an indicator of some kind - in simplest form, a marked face. As the indicator moves, it shows the passage of time in hours. When the length of the hour changed from season to season, a different water clock was needed for each month. Ancient peoples solved this problem in various ways, such as having different marked faces for each month. In that way the water clock was never far out of line with the sundial, which also remained in use. Later, instead of modifying water clocks to change with the seasons, sundials were constructed to show hours of the same length all year.
In the eighth century AD, the Chinese began to fashion water clocks with primitive escapements. The escapement is a ratchet that causes a wheel to move only so far and then stop. Continuous motions is replaced with discrete "ticks". By the beginning of the fourteenth century, the concept of an escapement was known in Europe where it was used to slow down the motion of a falling weight attached to it by a cord or chain. This motion was converted with gears to turn the hands of the clock. Mechanical clocks using escapements and weights were gradually improved and put into towers all over Europe.
1215 A.D.
King John is forced by English barons to sign the Magna Carta. Among other provisions, a unified system of measures is introduced.
1350 A.D.
England's King Edward I decreed that three grains of barley, dry and round, laid end to end, represented one inch. This somewhat equivocal "standard" remained in effect for hundreds of years until the 19th century.
1590 A.D.
Dutch eyeglass maker Hans Janssen and his son put two lenses at opposite ends of a tube and used them to examine tiny objects, marking the creation of the first compound microscope.
1592 A.D.
Galileo dipped a tube of air into a container of colored liquid to make the first crude thermometer.
1602 A.D.
Richard More, a scholarly London carpenter, gave an interesting account of the status of the carpenter's rule in a book in which he criticized the lack of standardization.
1631 A.D.
Pierre Vernier introduces his invention for precision measurement, known today as the Vernier scale.
1637 A.D.
Townsmen of the Hartford, CT Settlement ordered that each colony submit a measure to the next meeting of the court so that a consistent standard would be established. Eight years later, with additional towns added to the colony, there was a reassessment of the town weights and measures so that they could be compared together and made equal. A fine of 12 pence was imposed in 1647 for the sale of any commodity not measured by a rule or scale approved by the town clerk. He was required to be certain that rules were made of seasoned wood before affixing his seal and to break or demolish such weights, yards or measures as are defective.
1641 A.D.
English astronomer Gascoigne invents the cross hair which began the conversion of the telescope from a mere viewing device to precision measuring instrument.
1648 A.D.
First application of a screw as measuring element by William Gascoigne.
1660 A.D.
Italian Alcohol Thermometer
1670 A.D.
Gabriel Mouton, the vicar of St. Paul’s Church in Lyon, proposed a comprehensive decimal system of weights and measures using for the first time a base unit from the physical universe rather than the human body. This decimal system was the foundation of the metric system.
1683 A.D.
Dutch instrument maker Antony van Leeuwenhoek was making the world's first high powered precision microscopes.
Before the seventeenth century, it was almost impossible to perform precise measurements on anything. Although length and mass could be measured with a reasonable degree of accuracy, chemists did not realize the power of the balance, which was used primarily by assayers. Time could only be measured in large intervals. Temperature and fluid pressure could not be measured in numbers at all.
Galileo changed this. In 1581, when he was only 16, he noticed that the period of a pendulum appeared to be controlled solely by its length. This discovery led to the manufacture of good pendulum clocks by the end of the seventeenth century. In 1586, Galileo published his invention of a hydrostatic balance.
In 1600, he built the first primitive tool for measuring temperature. This was refined into a workable thermometer and put into modern form by German physicist Gabriel Fahrenheit in 1714. It was Galileo who suggested to Evangelista Torricelli the investigation that led to the barometer. Galileo's telescopes inspired others to build astronomical telescopes, which in turn led to the micrometer screw. Telescopes used in surveying also inspired the vernier system for making accurate measurements of angles.
1742 A.D.
Swedish astronomer Anders Celsius devised the temperature scale that bears his name and was later adopted in many countries as part of the metric system.1775 A.D.
British inventor Jesse Ramsden’s circular dividing engine revolutionized instrument making. Ramsden’s London shop produced highly accurate sextants, micrometers, and balances. His precision theodolite was used in the trigonometric survey geographically linking England and the Continent.
1780 A.D.
The Industrial Revolution Begins
Double Caliper
The legs measured the inner diameter, the upper part the outerDouble Caliper
Cabinetmaker’s tool for measuring the diameter of work as it turned at the lathe.Lumber Caliper
An itinerant log-rule maker, William Greenlief, fashioned this measurement device for lumberman. The wheel measures the length of a log, five feet to each rotation. The caliper measures the diameter of the log in inches. The scale on the rule gives a figure for the quantity of wood that can be obtained from the felled tree. Calipers were scaled to read in cord measure of swan logs, in cubic feet, or in board feet of sawn lumber. Length overall, 541/2 inches.Traveller
Used by iron smiths to measure wooden wheel rims.
1791 A.D.
The metric system of measurement is proposed in France.
1792 A.D.
Jean-Babtiste Delambre and Pierre Mechain begin their measurement of the arc of the meridian from Dunkirk to Barcelona, leading to the establishment of a uniform system of measures.
1805 A.D.
"Lord Chancellor" micrometer with a 1/10,000 inch resolution of indication from Henry Maudslay.
1820 A.D.
British Parliament passed a weights and measures act that defined all measurement in "Imperial Units" based on the yard and pound.
As early as 1670, when Jean Picard was establishing a modern value for the length of the earth’s meridian. It was suggested that measurement should be based on the meridian. That measurement, a unit of length called the meter, was established as one ten millionth of the length of the distance from the pole to the equator. A basic unit of mass, called the gram, was also established. It was based on a volume of pure water at a given temperature.
Weights and measures larger or smaller than a gram or meter are related to those units by a decimal system.
Despite its advantages, nations were slow to abandon customary measures for the metric system. Even in France where the system was developed, the change did not come easily. By 1875, however,the metric system was sufficiently established to make it necessary to set up an International Bureau of Weights and Measures to oversee it.
The bureau decided that scientific measurements could not be performed accurately if length was defined in terms of the size of Earth and mass in terms of pure water. Instead, the bureau replaced these measurements with a standard length on a platinum-iridium bar and a standard mass of platinum-iridium.
1833 A.D.
Brown & Sharpe Founded by Joseph Brown
1843 A.D.
Stanley Rule & Level Company Established
Lucian Sharpe joins Joseph Brown as an apprentice1848 A.D.
Patent from Laurent Palmer, France, for "un calibre á vis et á vernier circulaire" (external micrometer)
A screw advances a tiny distance with each full turn. When combined with a graduated scale, this principle becomes an accurate method for measuring small distances. Frenchman Jean Palmier was the first to put this concept into practical use in his screw gage (later called the micrometer), in 1848.Blacksmith-made squares of the 17th century were typically hand-forged tools. Blade and tongue are hammer-welded at the joint and numerals and graduations were hand struck Sir Joseph Whitworth developed his measuring machine about this time. In the original Whitworth workshop measuring machine the divisions on the micrometer wheel represented 10,000ths of an inch. The screw had 20 threads to the inch, and the wheel was divided into 500. The 500 multiplied by the 20 gives for each division the 10,000th of an inch.
1851 A.D.
Brown & Sharpe’s Vernier Caliper is introduced
1867 A.D.
Davis Levels. Adjustable spirit level, plumb, and inclinometer are combined in these iron tools patented in 1867, made for carpenters and machinists.1868 A.D.
Brown & Sharpe Micrometer Caliper is mass-produced (world’s first).
1875 A.D.
What may be the first mechanical coordinate measuring machine was built by Brown & Sharpe in 1875 for the Herreshoff Company in Bristol, RI, the world’s best known builder of boats and racing yachts. It was used to lay out every winning America’s Cup defender from 1895 to 1920.1876 A.D.
Brown & Sharpe’s celebrated apprenticeship program established and eventually adopted as a model by the U.S. Dept. of Labor.
1878 A.D.
Brown & Sharpe develops a linear measuring machine.
1890 A.D.
Construction of the first dial gages.
Ernst Abbe worked out the comparator’s principle.
Henry Leland leaves Brown & Sharpe where he began his career as an apprentice toolmaker in 1872, to eventually found the Lincoln Motor Car Company. Brown & Sharpe loaned Leland $2000, as a token of appreciation for his 18 years of services.
1904 A.D.
Patent delivered to C.E. Johansson for a "combination gauge block set"
1917 A.D.
Pneumatic length measuring instrument
Measuring with Waves
Possibly the most accurate form of measurement is based on the interaction of one wave with another. The principles involved are the same whether the waves are of water, light, or sound. If two waves are exactly the same, they can be adjusted so that they will cancel each other or increase each other. If the waves are not exactly the same, superimposing them will produce bands of brightness and darkness, called an interference pattern. Using an interference pattern to make measurements is called interferometry.
Among the first to use interferometry in measurement was Albert Michelson in 1881. By 1887, he and Edward Morley had used the concept to conduct one of the most famous experiments in science. They established through experimental data that the velocity of light is not affected by the movement of Earth through space. This discovery helped make acceptable Einstein's theory of relativity, which included the concept that the velocity of light in a vacuum is a universal constant.
1923 A.D.
Interference comparator for measuring gauge blocks
1931 A.D.
First electron microscope invented by German Physicist Ernst Ruska. Today they are a vital research tool in the laboratory and industry1935 A.D.
Electrical length measuring instrument with inductive probes from Bauer
1938 A.D.
Mikrokator manufactured by C.E. Johansson
1944 A.D.
Brown & Sharpe introduces the Electronic Gage1957 A.D.
TESAMASTER external micrometer
1963 A.D.
The first electronic measuring machine in the world: "ALPHA" designed and built by DEA.
1978 A.D.
The digital vernier caliper is produced by Brown & Sharpe (world’s first).1981 A.D.
MICRO-HITE height gauge
1988 A.D.
Metrology Grant Program established by Brown & Sharpe which introduced-metrology education to over 100 colleges, universities, vocational and high schools
1995 A.D.
Modern high-speed CMMs and process control robots, introduced by Brown & Sharpe Measuring Systems, accurately inspect workpieces as large as car bodies.Measurement In The Computer Age
The advent of inexpensive computing power in the 1970s and 1980s made it possible to not only automate many measurement procedures, but also quickly analyze vast amounts of dimensional data. An example of combining computing power and measurement is the SuperCOSMOS machine located at the Royal Observatory in Edinburgh. It incorporates a precision Leitz coordinate measuring machine and a sophisticated computer to collect dimensional and positional data about planetary bodies.Advances in software also make it possible to measure complex shapes such as gears, compressor vanes, and entire automobile bodies to extremely high accuracies. Analysis provides information that can be used to control manufacturing processes for genuine continuous quality improvement.
9/29/2007 | |
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