Measurement, English System of

Early measurements of length were based upon parts of the human body, which for a long time were accurate enough for daily calculations. It is still common for us to use hand, finger, and arm movements to accompany statements regarding size or dimension.

Lengthy History

The first known standard length was used around 3000 B.C.E. in Egypt. The Egyptians created the cubit, which was the distance between the elbow and the tip of the extended fingers. The Egyptians overcame the variation from one person to another by making a standard cubit equal to what is now 20.62 inches.

The Greeks adopted the Egyptian cubit as the basis of their system, but also had their own measure of length, the fathom, which was the distance from fingertip to fingertip with arms outstretched. The Greek historian Herodotus (484 B.C.E.–424 B.C.E.) stated that the fathom was equivalent to four cubits (or six feet). From Plutarch (46 C.E.–120 C.E.) it is known that the Parthenon of Pericles in Athens had a platform length of 100 feet. When measured with modern units, it is found that the Greek foot was 12.14 of today's inches. The foot was passed to the Romans who subdivided it into 12 equal parts that they called the uniciae.

European Measures

Medieval Europe was greatly influenced by the Roman system of units. Nevertheless, regional variations over the centuries resulted in a number of standard lengths. In the ninth century, Charlemagne tried to impose a uniform unit of length throughout Europe but failed due to people's reluctance to accept new units.

Charlemagne's efforts, however, did not go unrewarded and over the next few centuries the great trade fairs of Europe always had a Keeper of the Fair whose unit of length was compulsory for all commercial transactions within the fair grounds. The most prestigious unit of length was the Ell of Champagne, which was 2 feet 6 inches long, and was used in most of Europe as the standard measure for cloth, the most valuable of all trade goods at that time.

Royal Standards

An early attempt to standardize units in England resulted in a return to the royal standard, with the ell being equal in length to King Henry I's (1068–1135) own right arm. Present-day knowledge of the use of the royal arm is from the writings of William of Malmesbury (1095–1143), who has proven to be a reliable source for historical data. This ell was a larger measure than that used in cloth measuring, and eventually it became the yard.

By tradition, the yard of Henry I was the distance from the royal nose to the outstretched fingertips of the royal's right hand. The length was also chosen to ensure that 5½ yards equaled a rod, the fundamental unit for measuring land. Because land was the greatest measure of wealth in the Middle Ages, this correspondence was of particular importance. The rod was the Saxon measure for land and the Norman conquerors wanted to ensure that the land holdings of Saxon allies and new Norman landlords were precisely understood.

The Saxon word aecer, from which the word "acre" is derived, meant a field, or sown land. An aecer was 4 rods wide and 40 rods long, with the latter measurement being known as a furlong. The aecer represented about 5 hours of plowing by a team of oxen, the maximum the team could be expected to do in a day.

Hints of Change. By the time of the Magna Carta in 1215, the standards in England varied so widely that the thirty-fifth clause of the charter specified measurements for the unit of length as well as the gallon and the pound.

The next major review of the English units of measure occurred under the Tudor dynasty. In 1491 Parliament ordered the construction of new standards for length, weight, and capacity. These new Exchequer standards were stored in the Treasury, and in 1495, copies of these standards were supplied to forty-three shire towns in England. There was no change from the earlier yard and a later recalibration of measures in the reign of Elizabeth I also left the yard unchanged from the traditional length.

To Change or Not to Change

Between the reign of Queen Elizabeth I starting in the late sixteenth century and 1824 there were many proposals to refine or change the system of measurement. Many were based on the scientific knowledge generated by the Renaissance and the Enlightenment. However, they all failed to gain acceptance because they lacked the support of the English Parliament. The arguments for rejecting any proposed change was the one still used in the twenty-first century: namely, that it would a very expensive change for merchants and manufacturers. These arguments were also used against moving toward a metric system that was tainted by its association with Napoleon's imposition of this system on Europe.

In the United States, Thomas Jefferson (1742–1826) reported to Congress in 1791 on weights and measures to be used in the new republic. He assumed that traditional measures would continue as they were well understood by the public, but he did try to recommend a decimal system of his own devising. In 1821 John Quincy Adams (1767–1848) reported to Congress that a uniform set of weights and measures was urgently required, and suggested that the metric system be adopted. This recommendation was not accepted.

In England, the Imperial Weights and Measures Act of 1824 repealed all previous legislation with respect to weights and measures. However, this new Imperial System of Measurement did not create a complete break with the past. The standard yard was defined as the distance between the centers of two gold studs on a brass rod that was in the custody of the Clerk of the House of Commons. The temperature of the rod when a length was to be verified was to be 62° F. All measures of length were derived from this standard yard.

In 1834, the British Imperial Yard was destroyed by fire when the Houses of Parliament burned. A new Imperial Standard was designed and extensively tested to ensure that it matched perfectly the Elizabethan yard. The imperial standard yard still exists and is a solid gunmetal bar 38 inches long. The material used is an alloy of copper, tin, and zinc in the ratio 16:2.5:1. This alloy was selected because it gave a stiff bar and also had a very small change in length when the temperature varied. Near each end of the bar is a hole ⅜ inches in diameter with the two centers 36 inches apart. These holes were sunk halfway through the bar and have gold studs in them. On each of these gold studs are two lines parallel to the length of the bar and three other lines, 0.01 inch apart, at right angles to these parallels. The gap between the central line on each end is defined as the imperial standard yard. The entire bar rests on eight bronze rollers to avoid flexing. Copies of this new standard were presented to the United States, where the Office of Weights and Measures subsequently adopted it as a new standard, replacing all previous standards.

The Move to Metrics

In 1864 the use of metric units became permissible in England and in 1866 the metric system was made legal throughout the United States. Nine years later the United States went a step further and signed the Treaty of the Meter that established an international Bureau of Weights and Measures. In 1890 the signers of the Treaty each received exact copies of the International Prototype Meter and Kilogram. Three years later the Secretary of the Treasury issued the Mendenhall Order, which stated that the International Prototype Meter and Kilogram would be regarded as the fundamental standards from which all other measures in the United States would be derived. The yard was fixed at 0.91440183 meters and the pound at 0.4535924277 kilograms.

During the next 50 years, comparisons were made between the English and American standards. Though they were supposed to be identical, the English standard was found to be minutely smaller than that of the United States. The slight difference did not create problems in commercial transactions between the countries. During World War II, however, the need for precise aircraft parts showed that the discrepancy made a difference in other areas.

In 1959, Australia, Canada, New Zealand, South Africa, the United Kingdom, and the United States adopted a common standard for the inch:2.54 centimeters. However, the U.S. Coast and Geodetic Survey retained their established relationship of an inch equaling 2.540005 centimeters, which avoided extensive revisions to their charts and measurement records. The resulting foot is known as the U.S. Survey Foot. Since 1959, Australia, Canada, New Zealand, South Africa, and the United Kingdom have dropped the English yard as a legal unit of length and replaced it with the meter.

Measurement, English System of

Lengthy History

European Measures

Royal Standards

To Change or Not to Change

The Move to Metrics

Bibliography