HISTORY OF MEASUREMENT
The history of measurement is the history of mankind. Since man slew his first animal and built his first fire, his progress has been built on the foundation of measurement. The rate of his
progress throughout history has been closely related to his progress in the science of measurement.
However, man discovered at an early age that just the ability to measure was not enough. If our measurements were to be meaningful, they had to agree with the measurements of other men. This universal agreement about measurement units required the adoption of standards from which all men could derive the same units of measure. The problem was not a simple one. Throughout history there has been confusion because adopted standards have been changed, corrupted, or destroyed.
Natural standards of length such as the hand, span, palm, and digit were used from earliest times, but there is no record of any attempt to establish a permanent standard until the building of the great Khufu Pyramid in Egypt about 2900 B.C. The pharaoh Khufu was the first to decree that a standard unit of length be fixed. The standard chosen was made of black granite and was called the Royal Egyptian Cubit. History records its length as that of the ruling Pharaoh’s forearm and hand. (Length from the elbow to the tip of the 3rd digit, plus the width of the palm) It was also decreed that all working cubits (made of wood) be compared with the granite cubit every full moon, failure to do so was punishable by death.
Did this standard work? The answer must be an unequivocal, “yes,” when you consider that no side of the pyramid’s square base deviated from the average side length of 9000 inches by more than 1/20 of 1 percent. Although the history of Egyptians also knew a great deal about measuring angles, since each of the corners of the Great Pyramid is a perfect right angle within 3/1000 of a degree. Achieving this precision is difficult enough today even with all our modern tools and techniques.
Although the Egyptian priests swore by the great Ra to preserve the sacred cubit, they somehow failed because other cubits of different length came into use.
There are several interesting facts concerning the Egyptian Royal Cubit that make it similar to our modern standards. These features are:
1. It was defined and established by governmental decree; that is, the establishment was with some authority. This meant that all of the Artisans were required by law to use the same measuring system.
2. This standard was embodied in a physical object capable of application. By using a physical object rather than an abstract definition all the Artisans who used this system got the exact same meaning out of the standard rather than allowing the definition of the standard to be misinterpreted.
3. The unit was made of a very stable and durable material, one of the best available in those times. And, as such, would maintain the measurement accuracy for an indefinite period of time.
4. There were secondary standards that were compared at regular intervals to this primary standard. This would ensure that all of the WORKING STANDARDS, the measuring instruments that the Artisans used, had their TRACEABLE back to the original standard.
The Romans, like their predecessors, the Egyptian and Greeks, were also great architects. This is exemplified by the vast network of roads and aqueducts that they constructed. Since history indicates that these projects were completed in a relatively short length of time, it implies that construction must have started simultaneously at many points along the routes. This could only have been practical if there was an established standard measurement system for use by the various artisans who worked on the projects. If small reservoirs were to be prevented from forming along the route of the aqueducts, they must have been constructed with a constant incline from the distant mountain lakes to the coastal cities. It is inconceivable to think that the separated crews could have aligned all of their project so preciously had they not used measuring instruments that were compared or related to a set of established standards.
The Egyptians, Greeks, and Romans were, for a time, partially successful in establishing workable measurement systems and standards that were accepted and adhered to throughout their nations. In spite of all their short comings, these systems were relatively strong and workable, but most important, they were accepted and respected by the artisans that used them.
Man had just started this technological evolution when suddenly the great empires crumbled. Barbaric tribes invaded Europe, an action which history would later show, may have set man’s development back ten centuries. Man’s entrance into the Dark Ages stifled and destroyed that existing knowledge which had been so painfully earned.
The Dark Ages brought retrogression. Most measurement systems were forgotten with the exception of a few attempts by reigning monarchs to establish standards In Saxon times there was a yard bar at Winchester which King Edgar designated by decree as the sole official yard. This meant little, however, since measurement systems were so lacking that the very concept of a standard had been lost.
There was such a diversity of unrelated units that it staggers the imagination! Nearly all of the rulers tried to correct the situation since it seemed to require so little wisdom and power to set standards. All one had to do was decree that a yard was so long, that so many inches made a foot, so many feet a yard, and that all barrels used for measuring everything would contain 36 gallons, the same size as the king’s gallon. The rulers issued decrees, but were seldom able to achieve unity and order between their measurement standards.
The reigning king would send out his inspectors with copies of his standards, but trades people kept right on using whatever haphazard standards they had been using before. The standards and their copies were so poorly executed and of such meager ability that any system set forth disintegrated rapidly, and therefore was not trusted by the people.
The Arabic Numeral System introduced by Spain at the end of the 10th century ignited a spark, but it was not until the 14th century that the fire of scientific achievement started to blaze. Mankind’s technological reawakening was, at first, slow. Gunpowder came into use in 1346, a mechanical clock was built in 1360, DaVinci designed a screw cutting machine, and the printing press was invented. Man started to move; progress was being made.
Scientists and small village industries needed measuring instruments to explore their theories and to build better clocks and cannons. Together the scientists and instrument makers developed increasingly better measuring tools. In 1631 Pierre Vernier devised a scale that increased the readout capability of instruments by a factor of 10; in 1642 astronomer William Gascoigne devised a micrometer using screw threads. Even with all if these excellent measuring tools and techniques, the scientists and manufacturers were still handicapped because they could not refer to authoritative standards of equal or greater merit. What was needed was a common language of measurement, but there was not national or international system advanced enough to provide it.
James Watt, a Scottish inventor and instrument maker, who was close to the scientists of France and active in the Royal Society in England, urged that all scientists join together in promoting a completely new system of measurement. He proposed that this system be found on a standard unit of length from which all other measurements would be derived.
During the French Revolution, Prince Talleyrand, realizing that unity of weights and standards was one of the keys to national unit, directed the Royal Academy of Science to construct a new system based on the ideas proposed by Watt. Leading French scientist such as Laplace and Laoiser were summoned to help. There was no question on how the system was to be constructed, but what was the fundamental standard to be? They first considered TIME, proposing to derive the unity of length from the swing of a pendulum. This idea was rejected, partly because existing techniques for this measurement did not offer sufficient precision, and partly because it could not be reproduced with absolute certainty due to variations in the earth’s gravitational pull at different locations. They decided instead to derive the unit of length from a dimension of the earth. The meter, from the Greek word, METRON, meaning measure, was to be the basic distance from the equator to the North Pole. Since this distance was already known with fair precision, a provisional unit was adopted at once.
The agreement on and implementation of the metric system should have brought with it unification of measurements throughout Europe, but it, like its predecessors, failed. The metric
system was born during the French Revolution, and with the death or imprisonment of many of its founders, it fell into disuse.
The United States, having won its independence, inherited the problems of Europe. The founders of the constitution recognized the need for acceptable standards and with good intent vested the power with Congress “to fix the standards of weights and measures.” George Washington urged the Congress to act, but Congress accomplished nothing. The United States
was infected with the same disease that for centuries had eaten away at the progress of Europe. Each state had its own system of measurement; a bushel of oats weighed 24 pounds in Connecticut, 32 in New Jersey, 33 ½ in Kentucky, and 36 pounds was the standard out in the Washington Territory.
In 1807 Congress decided to have a survey made of the coast and formed the Coast Survey under the Treasury Department. Ferdinand R. Hassler, who was then a mathematics instructor at West Point, submitted an acceptable proposal to the Secretary of the Treasury was chosen as the first superintendent of the Coast Survey. When Hassler arrived in Washington he found an impressive title but no funds, for Congress had neglected to provide any money for the survey. Hassler decided to act, and without the slightest authority he determined what his—or rather our—national standards should be and began manufacturing copies of these standards for distribution to the state governments.
The standard unit of length which Hassler chose was a bar made by Edward Troughton, an English instrument maker. Although he knew that this particular bar had never been compared to the Parliamentary Yard, he decided that if any discrepancy was later discovered, the Parliamentary Yard would be the ultimate authority. He never got a chance to compare the original, however, because the Parliamentary Yard was destroyed by fire in 1834.
The Parliamentary Yard was ultimately restored and reliable copies were made for safe keeping and distribution. Two of the bars were sent to the United States. One of them, Bronze No. 11, was compared with Hassler’s Troughton scale and found to be0.00087 inch shorter. The Troughton scale was discarded, and for a time Bronze No. 11 became the accepted standard of length in the United States.
While not gaining popular acceptance in the United States, the complete metric system was slowly being adopted throughout Europe. In 1875, seventeen nations, including the United States, held an International Conference on Weights and Measures, and on May 20th of the same year signed the “Treaty of the Meter.” Committees were appointed to construct permanent standards that would be technically superior to those made during the French Revolution. The treaty also provided for an International Bureau of Weights and Measures to be established on neutral ground in Sevres, France.
The construction work completed in 1889, and the best of several prototype meter bars and kilograms were chosen to be the ultimate authority for the meter and kilogram. These two specimens were deposited for safety in an underground vault beneath the neutral ground provided by the treaty. They were undisturbed during both world wars.
Other meter and kilogram prototypes were distributed by lot among the treaty nations. Meter Bar No. 27 and Kilogram No. 20 were unpacked at a ceremony in the office of President Benjamin Harrison, and in 1893 they were accepted by the Congress of the United States as our FUNDAMENTAL national standards.
This ceremony, though impressive, was really meaningless. The industries of the United States were beginning to prepare for mass production, but history had shown too well that mass production cannot occur within the confines of a single factory. Each industry must be able to utilize the working products of other factories if interchangeability and total mass production were to become a reality.
While the newly adopted meter and kilogram standards were still in their shipping crates, there were over 100 different types and sizes of electrical lamp bases being used in American homes. This nonconformity of supposedly similar items was the rule rather than the exception. Agreements between manufactures and industries had been attempted, but the standards on which they had sought to build were still uncertain. The existing Office of Weights and Measures simply could not cope with the problem. Most European nations had built fine national laboratories to regulate measurements and standards and to act as an overseer of uniformity. American was falling behind.
The problem was an urgent one, and Congress finally acted. In 1901, a law was passed creating the National Bureau of Standards, now the National Institute of Standards and Technology (NIST). The Bureau was to have custody of existing standards and to create new standards as required. Today NIST maintains over 800 different standards in addition to conducting basic research in many related fields.
It took man 5,000 years to evolve from the Royal Egyptian Cubit to his first defined standard, the meter, which was adopted about 1900. Consider for a moment the rate of his progress since he became armed with this new weapon. Each era of history considered its standards to be ultimate at the time. Is our present day confidence in our ability justified, or will future generations look back on the twentieth century as the Dark Ages of their history.