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United States Customary System

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❶The cubic inch , cubic foot and cubic yard are commonly used for measuring volume.

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Second, the reciprocal performances of the parties must in some sense be equal in value. The bond of reciprocity unites men, not simply in spite of their differences but because of their differences. Because the source of recognition of customary law is reciprocity, private property rights and the rights of individuals are likely to constitute the most important primary rules of conduct in such legal systems.

After all, voluntary recognition of laws and participation in their enforcement is likely to arise only when substantial benefits from doing so can be internalized by each individual.

Punishment is frequently the threat that induces recognition of law imposed from above, but incentives must be largely positive when customary law prevails. Individuals must expect to gain as much or more than the costs they bear from voluntary involvement in the legal system. Protection of personal property and individual rights is a very attractive benefit. A potential action by one person has to affect someone else before any question of legality can arise; any action that does not, such as what a person does alone or in voluntary cooperation with someone else but in a manner that clearly harms no one, is not likely to become the subject of a rule of conduct under customary law.

But collective action can be achieved through individual agreements, with useful rules spreading to other members of a group. Demsetz explained that property rights will be defined when the benefits of doing so cover the costs of defining and enforcing such rights.

Such benefits may become evident because a dispute arises, implying that existing rules do not adequately cover some new situation. The parties involved must expect the benefits from resolving the dispute e. Dispute resolution can be a major source of legal change since an adjudicator will often make more precise those rules about which differences of opinion exist, and even supply new rules because no generally recognized rules cover a new situation.

If the relevant group accepts the ruling it becomes part of customary law, but not because it is coercively imposed on a group by some authority backing the court.

Thus, good rules that facilitate interaction tend to be selected over time, while bad decisions are ignored. Dispute resolution is not the only source of legal evolution under customary law. Individuals may observe others behaving in a particular way in a new situation and adopt similar behavior themselves, recognizing the benefit of avoiding confrontation.

Institutions for enforcement similarly evolve due to recognition of reciprocal benefits. Consider the development of dispute resolution procedures. No state- like coercive authority exists in a customary system to force disputants into a court.

Because rules of customary law are in the nature of torts, the aggrieved party must pursue prosecution. Under such circumstances, individuals have strong reciprocal incentives to form mutual support groups for legal matters. The makeup of such groups may reflect family as it frequently did in primitive societies , religion as in some primitive groups , geographic proximity as in Anglo-Saxon England , functional similarity as with commercial law , or contractual arrangements e.

The group members are obligated to aid any other member in a valid dispute, given that the member has fulfilled his obligations in the past. Thus, ability to obtain support in a dispute depends on reciprocal loyalty. Should a dispute arise, reciprocal support groups give individuals a position of strength. This does not necessarily mean, however, that disputes are settled by warfare between groups. Violence is a costly means of solving a dispute: Consequently, arrangements and procedures for non-violent dispute resolution should evolve very quickly in customary law systems.

The impetus for accepting adjudication in a customary legal system as well as in an authoritarian system is the omnipresent threat of force, but use of such force is certainly not likely to be the norm. Rather, an agreement between the parties must be negotiated. The Weights and Measures Act tidied up a number of shortcomings in the Act. The Weights and Measures Act of overhauled the inspection regime of weights and measures used in trade.

The act also reaffirmed the use of the brass standard yard and platinum standard pound as the standards for use in the United Kingdom, reaffirmed the use of apothecaries measures in the pharmaceutical industry, reaffirmed the definition of the gallon, removed the Troy pound from the list of legal units of measure, added the fathom to the list of legal units and fixed the ratio of metric to imperial units at one metre being equal to The Weights and Measures Act of effectively prohibited the use of metric weights for trade, the United Kingdom having declined to sign the Convention of the Metre three years previously.

The standard imperial yard was not stable — in its rate of shrinkage was quantified and found to be one part per million every 23 years. Broch , director of the BIPM replied that he was not authorised to perform any such calibrations for non-member states. Under the Weights and Measures Act of custody of the standard yard and pound and custody of the administration of weights and measures was entrusted to the Exchequer but verification was administered locally.

The Act formally described the office and duties of Inspectors of Weights and Measures and required every borough to appoint such officers and the Act passed responsibility for weights and measures to the Board of Trade. After the passage of the Act, weights and measures in the United Kingdom remained relatively unchanged until after the Second World War. By the middle of the century the difference of 2 parts per million between the British and US standard yards was causing problems—in a tolerance of 10 parts per million was adequate for science, but by this tolerance had shrunk to 0.

Metrication in the United Kingdom began in the mids. Initially this metrication was voluntary and by many traditional and imperial units of measure had been voluntarily removed from use in the retail trade. The Weights and Measures Act of formalized their removal for use in trade, though imperial units were retained for use on road signs and the most common imperial weights such as the foot, inch, pound, ounce, gallon and pint continued to be used in the retail trade for the sale of loose goods or goods measured or weighed in front of the customer.

When colonies attained dominion status, they also attained the right to control their own systems of weights and measures. India [23] and Hong Kong [24] supplemented the imperial system of units with their own indigenous units of measure, parts of Canada [25] and South Africa [26] included land survey units of measure from earlier colonial masters in their systems of measure while many territories used only a subset of the units used in the United Kingdom—in particular the stone , quarter and cental were not catalogued in, amongst others, Australian, [27] Canadian [28] and Indian [23] legislation.

The standardization of the yard in required not only agreement between the United States and the United Kingdom, but also of Canada, Australia, New Zealand and South Africa, all of whom had their own standards laboratories.

Prior to their declaration of independence in , the thirteen colonies that were to become the United States used the English system of measurement. During the First Congress of the United States in , Thomas Jefferson was detailed to draw up a plan for the currency and weights of measures that would be used in the new republic. In his response in he noted that the existing system of measure was sound but that control of the base artefact was not under the control of the United States.

His report suggested a means of manufacturing a local standard and also left the way open for an adoption of a decimal-based system should this be appropriate. For many years no action was taken at the federal level to ensure harmony in units of measure — the units acquired by the early colonists appeared to serve their purpose.

In Ferdinand Hassler was dispatched to Europe by the Treasury to acquire measuring instruments and standards. In Albert Gallatin, United States minister at London acquired an "exact copy" of the troy pound held by the British Government which in was adopted as the reference copy of weight in the United States. In John Quincy Adams , then Secretary of State submitted a report based on research commissioned by the Senate in which recommended the adoption of the metric system.

Congress did nothing and in the Treasury adopted the yard of 36 inches as the unit of length for customs purposes, the avoirdupois pound of grains as the unit of weight and the gallon of cubic inches the "Queen Anne gallon" and the bushel of Throughout the nineteenth century individual states developed their own standards and in particular a variety of bushels based on weight mass rather than volume emerged, dependent on both commodity and state.

This lack of uniformity crippled inter-state trade and in the National Bureau of Standards called a meeting of the states to discuss the lack of uniform standards and in many cases, a means of regulatory oversight. In the conference published its first model standards. Other commodities at the exchange are reckoned in pounds, in short tons or in metric tons. One of the actions taken by Congress was to permit the use of the metric system in trade , made at the height of the metrication process in Latin America.

In the administration of weights and measures was handed to a federal agency, the National Bureau of Standards, which in became the National Institute of Standards and Technology. During the twentieth century the principal change in the customary system of weights and measures was an agreement between NIST and the corresponding bodies in Australia, Canada, New Zealand, South Africa and the United Kingdom, signed in , that redefined the yard and the pound in terms of the metre and the kilogram respectively.

These new units became known as the international yard and pound. Congress has neither endorsed nor repudiated this action. Imperial and US customary units have long been used in many branches of engineering. Two of the earliest such units of measure to come into use were the horsepower and the degree Fahrenheit. The British thermal unit Btu is defined as the heat needed to raise the temperature of one pound of water by one degree Fahrenheit.

In a committee of the British Association for the Advancement of Science under the chairmanship of William Thomson Lord Kelvin introduced the concept of a coherence into units of measure and proposed the names dyne and erg as the units of force and work in the CGS system of units. Both systems depend on the gravitational acceleration , and use the pound-force as the unit of force but use different approaches when applying Newton's laws of motion.

In the BG system, force, rather than mass is a base unit while the slug is a derived unit of inertia rather than mass. Both these approaches led to slight variations in the meaning of the pound-force and also of the kilogram force in different parts of the world. Various countries published standard values that should be used for g and in the CGPM published a standard value for g that should be used in the "International Service of Weights and Measures", namely 9.

Newton's second law in these systems becomes:. The standard yard and [Troy] pound were lost in when a fire partially destroyed the Palace of Westminster. Unlike the previous standard, the new pound standard, made of platinum, was a pound avoirdupois. Scratch marks on the plugs denoted the length of the yard.

Following the debacle over the different gallons that had been adopted by the United States and the United Kingdom thirty years earlier, one of the copies of the standard yard and avoirdupois pound known in the United States as the "Mint pound" was offered to and accepted by the United States Government. In the years that followed the passing of the Act, the standard imperial yard was found to be shrinking at a rate, confirmed in , to be nearly one part per million every 30 years.

The "Mint pound" was also found to be of poor workmanship. In the United States Government legalised use of metric units in contract law, defining them in terms of the equivalent customary units to five significant figures which was sufficient for purposes of trade. In addition, the definitions of both the yard and the pound in terms of the artifacts held by the British Government was reaffirmed giving both the yard and the pound two different definitions.

These legal and technical discrepancies, described by McGreevy pg as being "unsound" led to the Commonwealth Science Conference of Agreement was reached by the standards laboratories in to redefine the yard and the metre as.

The final digit of the value chosen for the pound was chosen so as to make the number exactly divisible by 7, making the grain exactly This agreement was ratified by the United Kingdom in while Canada pre-empted the decision by adopting these values in , nine years ahead of the full international agreement. The United States Congress has neither ratified nor repudiated the agreement.

Prior to the imperial and customary yard and the pound were sufficiently close to each other [Note 5] that for most practical purposes the differences in the sizes of units of length, area, volume and mass could be disregarded, though there were differences in usage - for example, in the United States short road distances are specified in feet [63] while in the United Kingdom they are specified in yards [64] The introduction of the international yard in caused small but noticeable effects in surveying in the United States which resulted in some states retaining the original definitions of the customary units of measure which are now known as the survey mile, foot, while other states adopted the international foot.

When using customary units, it is usual to express body weight in pounds, but when using imperial units, to use stones and pounds. In his Plan for Establishing Uniformity in the Coinage, Weights, and Measures of the United States , Thomas Jefferson , then secretary of state , identified 14 different gallons in English statutes varying in size from to cubic inches 3. Sixteen US fluid ounces make a US pint 8 pints equals 1 gallon in both customary and imperial systems.

Twenty imperial fluid ounces make an imperial pint, the imperial fluid ounce being 0. The US Customary system of units makes use of set of dry units of capacity that have a similar set of names [Note 7] to those of liquid capacity, though different volumes - the dry pint having a volume of The imperial system of measure does not have an equivalent to the US customary system of "dry measure".

The tables below catalogue the imperial units of measure that were permitted for use in trade in the United Kingdom on the eve of metrication [67] [68] and the customary "units of measurement that have traditionally been used in the United States".

Prior to metrication, the units of measure used in the Ireland were the same as those used in the United Kingdom while those used in the British Commonwealth and in South Africa were in most cases a subset of those used in the United Kingdom with, in certain cases, local differences.

Unless otherwise specified, the units of measure quoted below were used in both the United States, the United Kingdom.

The SI equivalents are quoted to four significant figures. At the time the discrepancy of about two parts per million was considered to be insignificant. In , the United Kingdom, United States, Australia, Canada and South Africa standardised their units of length by defining the "international yard" as being 0.

This change affected land surveyors in the United States and led to the old units being renamed "survey feet", "survey miles" etc. However the introduction of the metric-based Ordnance Survey National Grid Surveyors in the United Kingdom in meant that British surveyors were unaffected by the change. The introduction of the international yard in had no effect on British measurements of area, however US measurements of land area, as opposed to other measurements of area such as pounds per square inch continued to be based on the US statute yard.

Several of the units of liquid volume or capacity have similar names, but have different volumes — and in the case of fluid ounces and pints, different relations. In addition the definitions of the imperial and US gallons are based on different concepts — the imperial gallon is defined in terms of the volume occupied by a specified mass of water, while the US gallon is specified in terms of cubic linear measure.

Units of weight in both the imperial and US customary system always used the same standard, though differences in multiples of the avoirdupois pound developed in the nineteenth century. Both systems used the three different scales — the avoirdupois system for general use, the troy system for precious metals and the apothecaries system in the pharmacy industry.

The term "weight" and "mass" are used interchangeably in the imperial and US customary systems, though since the linking of the pound to the kilogram in 19xx, the pound technically became a mass, not a weight. Apothecaries weights were used in the pharmaceutical industry and have remained almost unchanged since the Middle Ages — the Apothecaries pound and ounce being the same as the Troy pound and ounce, but each system having different sub-units.

In the United Kingdom, these units are of historic interest only, having been replaced by metric units in The names of most derived units of measure in the imperial and US customary systems are concatenations of the constituent parts of the unit of measure, for example the unit of pressure is the pounds [force] per square inch.

Apart from the poundal , most of the named units of measure are non-coherent , but were adopted due to traditional working practice. In addition to those catalogued above, there are literally hundreds of other units of measure in both the imperial and the US customary system of measurement — many are specific to a particular industry of application.

Such units could, in theory, be replaced by general units of the same dimension, for example the barrel 42 US gallons, The definitions of potential difference volt , electric current ampere , electrical resistance ohm were defined in terms of metric units, international agreement having been reached at a series of IEC Congress in Chicago between and when the electrical industry was in its infancy.

Similarly, the units of measurement used in the radiological industry were defined in terms of metric units, agreement first having been reached at the second International Congress of Radiology at Stockholm Since its inception, the metric system has displaced the traditional system of units in many countries.

In the s a metrication program was initiated in most English-speaking countries, resulting in either the partial or total displacement of the imperial system or the US customary system of measure in those countries. The current status of imperial and US customary units, as summarised by NIST , is that "the SI metric system is now the official system of units in the United Kingdom, while the customary units are still predominantly used in the United States". The situation is however not as clear-cut as this.

In the United States, for example, the metric system is the predominant system of measure in certain fields such as automobile manufacture even though customary units are used in aircraft manufacture.

From Wikipedia, the free encyclopedia. United States customary units. Comparison of the imperial and US customary measurement systems. As of 24 April , troy ounces are still legal for the sale of precious metals. The gallons ranged from the wine gallon of cubic inches 3.

The Measure of Humanity. The Basis of Measurement. Report upon Weights and Measures. Office of the Secretary of State of the United States. Seaby's Standard Catalogue — British Coins. Report of the 50th National Conference on Weights and Measures US Department of Commerce: National Bureau of Standards.

Retrieved 28 May Retrieved 28 June The statutes at large: The statutes at large. Retrieved November 30, British Weights and Measures: A History from Antiquity to the Seventeenth Century. University of Wisconsin Press. Society for the Diffusion of Useful Knowledge. Metrology; or, An exposition of weights and measures. His Majesty's Statute and Law Printers. Retrieved 12 June Forty-second National Conference on Weights and Measures. His Majesty's Stationery Office.

Retrieved 16 June Retrieved 9 July From Artefacts to Atoms: The London Gazette Weights and Measures Act as amended see also enacted form , from legislation.


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United States customary units are a system of measurements commonly used in the United States. The United States customary system (USCS or USC) developed from English units which were in use in the British Empire before the U.S. became an independent country.

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The imperial and US customary systems of measurement are two closely inter-related systems of measurement both derived from earlier English system of measurement units which can be traced back to Ancient Roman units of measurement, and Carolingian and Saxon units of measure.

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unit of capacity in the British Imperial and U.S. Customary systems of measurement. In the British system the units for dry measure and liquid measure are identical; the single British pint is equal to cubic inches ( cubic cm) or one-eighth gallon. The bushel (bu) is a measurement of dry volume in the US Customary System. Two systems of weights and measures are derived from English Units: the US Customary System and the British Imperial System.