Purchase 12 flag sticks that are 20 feet long. Create an inch by inch measuring system on them. Do this from top to bottom. Follow it up with a foot by foot measuring system. Put on your life jacket. Gather your flag sticks, tape and your...more?
A flag is most of the time a piece of fabric with a distinctive design that is usually rectangular and used as a symbol, as a signaling device, or decoration. The term flag is also used to refer to the graphic design employed by a flag, or to its depiction in another medium.
The first flags were used to assist military coordination on battlefields, and flags have since evolved into a general tool for rudimentary signalling and identification, especially in environments where communication is similarly challenging (such as the maritime environment where semaphore is used). National flags are potent patriotic symbols with varied wide-ranging interpretations, often including strong military associations due to their original and ongoing military uses. Flags are also used in messaging, advertising, or for other decorative purposes. The study of flags is known as vexillology, from the Latin word vexillum, meaning flag or banner.
In antiquity, field signs or standards were used in warfare that can be categorized as vexilloid or "flag-like". Examples include the Achaemenid battle standard Derafsh Kaviani, and the standards of the Roman legions such as the eagle of Augustus Caesar's Xth legion, or the dragon standard of the Sarmatians; the latter was let fly freely in the wind, carried by a horseman, but judging from depictions it was more similar to an elongated dragon kite than to a simple flag.
During the High Middle Ages flags came to be used primarily as a heraldic device in battle, allowing more easily to identify a knight than only from the heraldic device painted on the shield. Already during the high medieval period, and increasingly during the Late Middle Ages, city states and communes such as those of the Old Swiss Confederacy also began to use flags as field signs. Regimental flags for individual units became commonplace during the Early Modern period.
During the peak of the age of sail, beginning in the early 17th century, it has been customary (and later a legal requirement) for ships to carry flags designating their nationality; these flags eventually evolved into the national flags and maritime flags of today. Flags also became the preferred means of communications at sea, resulting in various systems of flag signals; see, International maritime signal flags.
Use of flags outside of military or naval context begins only with the rise of nationalist sentiment by the end of the 18th century; the earliest national flags date to that period, and during the 19th century it became common for every sovereign state to introduce a national flag.
One of the most popular uses of a flag is to symbolize a nation or country. Some national flags have been particularly inspirational to other nations, countries, or subnational entities in the design of their own flags. Some prominent examples include:
National flag designs are often used to signify nationality in other forms, such as flag patches.
A civil flag is a version of the national flag that is flown by civilians on non-government installations or craft. The use of civil flags was more common in the past, in order to denote buildings or ships that were not manned by the military. In some countries the civil flag is the same as the war flag or state flag, but without the coat of arms, such as in the case of Spain, and in others it's an alteration of the war flag.
Several countries (including the United Kingdom and the Soviet Union) have had unique flags flown by their armed forces, rather than the national flag.
Other countries' armed forces (such as those of the United States or Switzerland) use their standard national flag. The Philippines' armed forces may use their standard national flag, but during times of war the flag is turned upside down. Bulgaria's flag is also turned upside down during times of war. These are also considered war flags, though the terminology only applies to the flag's military usage.
Large versions of the war flag flown on the warships of countries' navies are known as battle ensigns. In war waving a white flag is a banner of truce or surrender.
Four distinctive African flags currently in the collection of the National Maritime Museum in Britain were flown in action by Itsekiri ships under the control of Nana Olomu during conflict in the late 19th century. One is the flag generally known as the Benin flag and one is referred to as Nana Olomu's flag.
Among international flags are the Flag of the United Nations, the Olympic flag, the Paralympic flag, The EU flag and the World Flag.
Please see Gallery of flags by design
Flags are particularly important at sea, where they can mean the difference between life and death, and consequently where the rules and regulations for the flying of flags are strictly enforced. A national flag flown at sea is known as an ensign. A courteous, peaceable merchant ship or yacht customarily flies its ensign (in the usual ensign position), together with the flag of whatever nation it is currently visiting at the mast (known as a courtesy flag). To fly one's ensign alone in foreign waters, a foreign port or in the face of a foreign warship traditionally indicates a willingness to fight, with cannon, for the right to do so. As of 2009, this custom is still taken seriously by many naval and port authorities and is readily enforced in many parts of the world by boarding, confiscation and other civil penalties.
In some countries yacht ensigns are different from merchant ensigns in order to signal that the yacht is not carrying cargo that requires a customs declaration. Carrying commercial cargo on a boat with a yacht ensign is deemed to be smuggling in many jurisdictions. There is a system of international maritime signal flags for numerals and letters of the alphabet. Each flag or pennant has a specific meaning when flown individually. As well, semaphore flags can be used to communicate on an ad hoc basis from ship to ship over short distances. Traditionally, a vessel flying under the courtesy flag of a specific nation, regardless of the vessel's country of registry, is considered to be operating under the law of her 'host' nation.
Flags are usually rectangular in shape (often in the ratio 2:3, 1:2, or 3:5), but may be of any shape or size that is practical for flying, including square, triangular, or swallow tailed. A more unusual flag shape is that of the flag of Nepal, which is in the shape of two stacked triangles. Other unusual flag shapes include the flag of Ohio and the flag of Tampa.
Many flags are dyed through and through to be inexpensive to manufacture, such that the reverse side is the mirror image of the obverse (front) side, generally the side displayed when the flag is flying from the observer's point of view from left, the side of the pole, to right. This presents two possibilities:
Some complex flag designs are not intended for through and through implementation, requiring separate obverse and reverse sides if made correctly. In these cases there is a design element (usually text) which is not symmetric and should be read in the same direction, regardless of whether the hoist is to the viewer's left or right. These cases can be divided into two types:
Common designs on flags include crosses, stripes, and divisions of the surface, or field, into bands or quarters—patterns and principles mainly derived from heraldry. A heraldic coat of arms may also be flown as a banner of arms, as is done on both the state flag of Maryland and the flag of Kiribati.
The de jure flag of Libya under Muammar Gaddafi, which consisted of a rectangular field of green, was for a long period the only national flag using a single color and no design or insignia. However, other historical states have also used flags without designs or insignia, such as the Soviet Republic of Hungary, whose flag was a plain field of red.
Colors are normally described with common names, such as "red", but may be further specified using colorimetry.
The largest flag flown from a flagpole worldwide, according to Guinness World Records, is the Mexican national flag flown in Piedras Negras, Coahuila, Mexico. This flag was about 2058 square meters.
Vertical flags are sometimes used in lieu of the standard horizontal flag in central and eastern Europe, particularly in the German-speaking countries. This practice came about because the relatively brisk wind needed to display horizontal flags is not common in these countries.
The standard horizontal flag (no. 1 in the preceding illustration) is nonetheless the form most often used even in these countries.
The vertical flag (German: Hochformatflagge or Knatterflagge; no. 2) is a vertical form of the standard flag. The flag's design may remain unchanged (No. 2a) or it may change, e.g. by changing horizontal stripes to vertical ones (no. 2b). If the flag carries an emblem, it may remain centered or may be shifted slightly upwards.
The vertical flag for hoisting from a beam (German: Auslegerflagge or Galgenflagge; no. 3) is additionally attached to a horizontal beam, ensuring that it is fully displayed even if there is no wind.
The vertical flag for hoisting from a horizontal pole (German: Hängeflagge; no. 4) is hoisted from a horizontal pole, normally attached to a building. The topmost stripe on the horizontal version of the flag faces away from the building.
The vertical flag for hoisting from a crossbar or banner (German: Bannerflagge; no. 5) is firmly attached to a horizontal crossbar from which it is hoisted, either by a vertical pole (no. 5a) or a horizontal one (no. 5b). The topmost stripe on the horizontal version of the flag normally faces to the left.
Flags can play many different roles in religion. In Buddhism, prayer flags are used, usually in sets of five differently colored flags. Many national flags and other flags include religious symbols such as the cross, the crescent, or a reference to a patron saint. Flags are also adopted by religious groups and flags such as the Jain flag and the Christian flag are used to represent a whole religion.
As languages rarely have a flag designed to represent them, it is a common but unofficial practice to use national flags to identify them. Examples of this use include:
Though this can be done in an uncontroversial manner in some cases, this can easily lead to some problems for certain languages:
In this second case, common solutions include symbolising these languages by:
Thus, on the Internet, it is common to see the English language associated with the flag of the United Kingdom, or sometimes the flag of England, the flag of the United States or a US-UK mixed flag, usually divided diagonally. However, this practice is deprecated because it is often considered insulting.
Because of their ease of signalling and identification, flags are often used in sports.
Social and political movements have adopted flags, to increase their visibility and as a unifying symbol.
The socialist movement uses red flags to represent their cause. The anarchist movement has a variety of different flags, but the primary flag associated with them is the black flag. In the Spanish civil war, the anarcists used the red-and-black bisected flag. In the 1900s, the rainbow flag was adopted as a symbol of the LGBT social movements. Bisexual and transgender pride flags were later designed, in an attempt to emulate the rainbow flag's success.
Some of these political flags have become national flags, such as the red flag of the Soviet Union and national socialist banners for Nazi Germany. The present Flag of Portugal is based on what had been the political flag of the Portuguese Republican Party previous to the 5 October 1910 revolution which brought this party to power.
Flags are often representative of an individual's affinity or allegiance to a country, team or business and can be presented in various ways. A popular trend that has surfaced revolves around the idea of the 'mobile' flag in which an individual displays their particular flag of choice on their vehicle. These items are commonly referred to as car flags and are usually manufactured from high strength polyester material and are attached to a vehicle via a polypropylene pole and clip window attachment.
In Australia, Canada, New Zealand, Philippines, and the United Kingdom a pair of red/yellow flags is used to mark the limits of the bathing area on a beach, usually guarded by surf lifesavers. If the beach is closed, the poles of the flags are crossed. The flags are colored with a red triangle and a yellow triangle making a rectangular flag, or a red rectangle over a yellow rectangle. On many Australian beaches there is a slight variation with beach condition signaling. A red flag signifies a closed beach (or, in the UK, some other danger), yellow signifies strong current or difficult swimming conditions, and green represents a beach safe for general swimming. In Ireland, a red and yellow flag indicates that it is safe to swim; a red flag that it is unsafe; and no flag indicates that there are no lifeguards on duty. Blue flags may also be used away from the yellow-red lifesaver area to designate a zone for surfboarding and other small, non-motorised watercraft.
Reasons for closing the beach include:
A surf flag exists, divided into four quadrants. The top left and bottom right quadrants are black, and the remaining area is white.
Signal flag "India" (a black circle on a yellow square) is frequently used to denote a "blackball" zone where surfboards cannot be used but other water activities are permitted.
Railways use a number of colored flags. When used as wayside signals they usually use the following meanings (exact meanings are set by the individual railroad company):
At night, the flags are replaced with lanterns showing the same colors.
Flags displayed on the front of a moving locomotive are an acceptable replacement for classification lights and usually have the following meanings (exact meanings are set by the individual railroad company):
Additionally, a railroad brakeman will typically carry a red flag to make his or her hand signals more visible to the engineer. Railway signals are a development of railway flags.
A flagpole, flagstaff, or staff can be a simple support made of wood or metal. If it is taller than can be easily reached to raise the flag, a cord is used, looping around a pulley at the top of the pole with the ends tied at the bottom. The flag is fixed to one lower end of the cord, and is then raised by pulling on the other end. The cord is then tightened and tied to the pole at the bottom. The pole is usually topped by a flat plate or ball called a "truck" (originally meant to keep a wooden pole from splitting) or a finial in a more complex shape. Very high flagpoles may require more complex support structures than a simple pole, such as guy wires, or need be built as a mast.
Since 2011, the tallest free-standing flagpole in the world has been the Dushanbe Flagpole in Tajikistan, with a height of 165 m (541 ft), beating the formerly record holding National Flagpole in Azerbaijan (size: 162 m; 532 ft) and the North Korean flag at Kijŏng-dong (size: 160 m; 525 ft).
The tallest flagpole in the United Kingdom from 1959 until 2013 stood in Kew Gardens. It was made from a Canadian Douglas-fir tree and was 68.5 m (225 ft) in height.
Flagpoles can be designed in one piece with a taper (typically a steel taper or a Greek entasis taper), or be made from multiple pieces to make them able to expand. In the United States, ANSI/NAAMM guide specification FP-1001-97 covers the engineering design of metal flagpoles to ensure safety.
Hoisting the flag is the act of raising the flag on the flagpole. Raising or lowering flags, especially national flags, usually involves ceremonies and certain sets of rules, depending on the country. A flag-raising squad is a group of people, usually troops, cadets, or students, that marches in and brings the flags for the flag-hoisting ceremony. Flag-hoisting ceremonies involving flag-raising squads can be simple or elaborate, involving large numbers of squads. Elaborate flag-hoisting ceremonies are usually performed on national holidays.
Semaphore is a form of communication that utilizes flags. The signalling is performed by an individual using two flags (or lighted wands), the positions of the flags indicating a symbol. The person who holds the flags is known as the signalman. This form of communication is primarily used by naval signallers. This technique of signalling was adopted in the early 19th century and is still used in various forms today.
The colors of the flags can also be used to communicate. For example; a white flag means, among other things, surrender or peace, a red flag can be used as a warning signal, and a black flag can mean war, or determination to defeat enemies.
Orientation of a flag is also used for communication, though the practice is rarely used given modern communication systems. Raising a flag upside-down was indicative that the raising force controlled that particular area, but that it was in severe distress.
When blown by the wind, flags are subject to wave-like motions that grow in amplitude along the length of the flag. This is sometimes ascribed to the flag pole giving vortex shedding, however flags that are held by lanyards also can be seen to flap.
An inch (plural: inches; abbreviation or symbol: in or ″ – a double prime) is a unit of length in the imperial and United States customary systems of measurement. Historically an inch was also used in a number of other systems of units. Traditional standards for the exact length of an inch have varied in the past, but now the imperial or US customary inch is defined to be exactly 25.4 mm. There are 12 inches in a foot and therefore 36 inches in a yard.
The inch is a commonly used customary unit of length in the United States, Canada, and the United Kingdom. For the United Kingdom, guidance on public sector use states that since 1 October 1995, without time limit, that the inch (along with the foot) is to be used as a primary unit for road signs and related measurements of distance (with the possible exception of clearance heights and widths) and may continue to be used as a secondary or supplementary indication following a metric measurement for other purposes.
The international standard symbol for inch is in (see ISO 31-1, Annex A) but traditionally the inch is denoted by a double prime, which is often approximated by double quotes, and the foot by a prime, which is often approximated by an apostrophe. For example can be written as 3′ 2″. Subdivisions of an inch are typically written using dyadic fractions with odd number numerators; for example, would be written as ″ and not as 2.375″ nor as ″.
1 international inch is equal to:
The English word inch comes from Latin uncia meaning "one-twelfth part" (in this case, one twelfth of a foot); the word ounce (one twelfth of a troy pound) has the same origin. The vowel change from u to i is umlaut; the consonant change from c (pronounced as k) to ch is palatalisation (see Old English phonology).
In some other languages, the word for "inch" is similar to or the same as the word for "thumb"; for example, Catalan: inch, polze thumb; French: inch/thumb; Italian: inch/thumb; Spanish: inch, pulgar thumb; Portuguese: inch, polegar thumb; Swedish: inch, tumme thumb; Dutch: inch/thumb; Czech: inch/thumb; Slovak: inch/thumb; Hungarian: inch/thumb, Danish and Norwegian: / tommer inch/inches and tommel thumb. Given the etymology of the word "inch", it would seem that the inch is a unit derived from the foot unit in Latin in Roman times.
The earliest known reference to the inch in England is from the Laws of Æthelberht dating to the early 7th century, surviving in a single manuscript from 1120. Paragraph LXVII sets out the fine for wounds of various depths: one inch, one shilling, two inches, two shillings, etc. "Gif man þeoh þurhstingð, stice ghwilve vi scillingas. Gife ofer ynce, scilling. æt twam yncum, twegen. ofer þry, iii scill."
An Anglo-Saxon unit of length was the barleycorn. After 1066, 1 inch was equal to 3 barleycorn, which continued to be its legal definition for several centuries, with the barleycorn being the base unit. One of the earliest such definitions is that of 1324, where the legal definition of the inch was set out in a statute of Edward II of England, defining it as "three grains of barley, dry and round, placed end to end, lengthwise".
Similar definitions are recorded in both English and Welsh medieval law tracts. One, dating from the first half of the 10th century, is contained in the Laws of Hywel Dda which superseded those of Dyvnwal, an even earlier definition of the inch in Wales. Both definitions, as recorded in Ancient Laws and Institutes of Wales (vol i., pp. 184,187,189), are that "three lengths of a barleycorn is the inch".
King David I of Scotland in his Assize of Weights and Measures (c. 1150) is said to have defined the Scottish inch as the width of an average man's thumb at the base of the nail, even including the requirement to calculate the average of a small, a medium, and a large man's measures. However, the oldest surviving manuscripts date from the early 14th century and appear to have been altered with the inclusion of newer material.
Charles Butler, a mathematics teacher at Cheam School, in 1814 recorded the old legal definition of the inch to be "three grains of sound ripe barley being taken out the middle of the ear, well dried, and laid end to end in a row", and placed the barleycorn, not the inch, as the base unit of the English Long Measure system, from which all other units were derived. John Bouvier similarly recorded in his 1843 law dictionary that the barleycorn was the fundamental measure. Butler observed, however, that "[a]s the length of the barley-corn cannot be fixed, so the inch according to this method will be uncertain", noting that a standard inch measure was now (by his time) kept in the Exchequer chamber, Guildhall, and that was the legal definition of the inch. This was a point also made by George Long in his 1842 Penny Cyclopædia, observing that standard measures had since surpassed the barleycorn definition of the inch, and that to recover the inch measure from its original definition, in the event that the standard measure were destroyed, would involve the measurement of large numbers of barleycorns and taking their average lengths. He noted that this process would not perfectly recover the standard, since it might introduce errors of anywhere between one hundredth and one tenth of an inch in the definition of a yard.
The now obsolete Scottish inch (Scottish Gaelic: ), of a Scottish foot, was about 1.0016 imperial inches (about 2.5441 cm). It was used in the popular expression , in English "Give him an inch and he'll take an ell.", first published as "For when I gave you an inch, you tooke an ell." by John Heywood in 1546. (The ell, equal to 37 inches (about 94 cm), was in use in England until 1685.)
The current internationally accepted value for the imperial and US customary inch is exactly 25.4 millimetres. This is based on the international yard of exactly 0.9144 metres adopted through the International yard and pound agreement in 1959. Before the adoption of the international inch various definitions were in use. In the United Kingdom and most countries of the British Commonwealth][ the inch was defined in terms of the Imperial Standard Yard. The US adopted the conversion factor 1 metre = 39.37 inches by an act in 1866, and in 1893 Mendenhall ordered the physical realization of the inch be based on the international prototype metres numbers 21 and 27, which had been received from the CGPM together with the previously adopted conversion factor.
In 1930 the British Standards Institution adopted an inch of exactly 25.4 mm. The American Standards Association followed suit in 1933. By 1935 industry in 16 countries had adopted the "industrial inch" as it came to be known.
In 1946 the Commonwealth Science Congress recommended a yard of exactly 0.9144 metres for adoption throughout the British Commonwealth. This was adopted by Canada in 1951. The United States, the United Kingdom, Canada, Australia, New Zealand and South Africa signed a treaty agreeing to the same standards on 1 July 1959. This gives an inch of exactly 25.4 mm. However, the US retains the -metre definition for survey purposes creating a slight difference between the international and US survey inches.
The metric system is an internationally agreed decimal system of measurement that was originally based on the and the introduced by France in 1799. Over the years, the definitions of the metre and kilogram have been refined and the metric system has been extended to incorporate many more units. Although a number of variants of the metric system emerged in the late nineteenth and early twentieth centuries the term is now often used as a synonym for "SI" or the "International System of Units"—the official system of measurement in almost every country in the world.
The metric system has been officially sanctioned for use in the United States since 1866, but it remains the only industrialised country that has not adopted the metric system as its official system of measurement. Many sources also cite Liberia and Burma as the only other countries not to have done so. Although the United Kingdom uses the metric system for most official purposes, the use of the imperial system of measure, particularly in unregulated sectors such as journalism, is widespread.
Although the originators intended to devise a system that was equally accessible to all, it proved necessary to use prototype units under the custody of government or other approved authorities as standards. Control of the prototype units of measure was maintained by the French government until 1875 when it passed to an inter-governmental organisation—the General Conference on Weights and Measures (CGPM). It is now hoped that the last of these prototypes can be retired by 2014.
From its beginning, the main features of the metric system were the standard set of inter-related base units and a standard set of prefixes in powers of ten. These base units are used to derive larger and smaller units that could replace a huge number of other units of measure in existence. Although the system was first developed for commercial use, the development of coherent units of measure made it particularly suitable for science and engineering.
The uncoordinated use of the metric system by different scientific and engineering disciplines, particularly in the late 19th century, resulted in different choices of fundamental units, even though all were based on the same definitions of the metre and the kilogram. During the 20th century, efforts were made to rationalise these units and in 1960 the CGPM published the International System of Units which, since then, has been the internationally recognised standard metric system.
Although the metric system has changed and developed since its inception, its basic concepts have hardly changed. Designed for transnational use, it consisted of a basic set of units of measurement, now known as base units; derived units were built up from the base units using logical rather than empirical relationships while multiples and submultiples of both base and derived units were decimal-based and identified by a standard set of prefixes.
At the outbreak of the French Revolution in 1789, most countries and even some cities had their own system of measurement. Although different countries might have used units of measure with the same name, such as the foot, or local language equivalents such as pied, fuß and voet, there was no consistency in the magnitude of those units, nor in the relationships with their multiples and sub-multiples, much like the modern-day differences between the US and the UK pints and gallons.
The metric system was designed to be universal—in the words of the French philosopher Marquis de Condorcet it was to be "for all people for all time".:1 It was designed for ordinary people, for engineers who worked in human-related measurements and for astronomers and physicists who worked with numbers both small and large, hence the huge range of prefixes that have now been defined in SI.
When the French Government first investigated the idea of overhauling their system of measurement, the concept of universality was put into practice when, in 1789, Maurice de Talleyrand, acting on Condorcet's advice, invited John Riggs Miller, a British Parliamentarian and Thomas Jefferson, the American Secretary of State to George Washington, to work with the French in producing an international standard by promoting legislation in their respective legislative bodies. However, these overtures failed and the custody of the metric system remained in the hands of the French government until 1875.:250-253
Unit names are ordinary nouns and although they use the character set and follow the grammatical rules of the language concerned for example "", "", each unit has a symbol that is independent of language, for example "km" for "kilometre", "V" for "volts" etc.
In the metric system, multiples and sub-multiples of units follow a decimal pattern, a concept identified as a possibility in 1586 by Simon Stevin, the Flemish mathematician who had introduced decimal fractions into Europe. This is done at the cost of losing the simplicity associated with many traditional systems of units where division by 3 or 4 does not result in awkward fractions; for example one third of a foot is four inches, a simplicity that in 1790 was debated, but rejected by the originators of the metric system. In 1854, in the introduction to the proceedings of the [British] Decimal Association, the mathematician Augustus de Morgan, summarised the advantages of a decimal based system were over a non-decimal system thus: "In the simple rules of arithmetic, we practice a pure decimal system, nowhere interrupted by the entrance of any other system: from column to column we never carry anything but tens".
A common set of decimal-based prefixes that have the effect multiplication or division by an integer power of ten can be applied to units which are too large or too small for practical use. The concept of using consistent classical (Latin or Greek) names for the prefixes was first proposed in a report by the [French Revolutionary] Commission on Weights and Measures in May 1793.:89-96 The prefix kilo, for example, is used to multiply the unit by 1000, and the prefix milli is to indicate a one-thousandth part of the unit. Thus the kilogram and kilometre are a thousand grams and metres respectively, and a milligram and millimetre are one thousandth of a gram and metre respectively. These relations can be written symbolically as:
In the early days, multipliers that were positive powers of ten were given Greek-derived prefixes such as kilo- and mega-, and those that were negative powers of ten were given Latin-derived prefixes such as centi- and milli-. However, 1935 extensions to the prefix system did not follow this convention; the prefixes nano- and micro-, for example used prefixes with Greek roots. During the 19th century the prefix myria-, derived from the Greek word μύριοι (mýrioi), was used as a multiplier for (104).
When applying prefixes to derived units of area and volume that are expressed in terms of units of length squared or cubed, the square and cube operators are applied to the unit of length including the prefix, as illustrated here:
Prefixes are not usually used to indicate multiples of a second greater than 1; the non-SI units of minute, hour and day are used instead. On the other hand, prefixes are used for multiples of the non-SI unit of volume, the litre (l, L) such as millilitres (mL) or kilolitres (kL).
The base units used in the metric system must be realisable, ideally with reference to natural phenomena rather than unique artefacts. Each of the base units in SI is accompanied by a mise en pratique [practical realisation] published by the BIPM that describes in detail at least one way in which the base unit can be measured. Where possible, definitions of the base units were developed so that any laboratory equipped with proper instruments would be able to realise a standard without reliance on an artefact held by another country. In practice, such realisation is done under the auspices of a mutual acceptance arrangement (MAA).
In the original version of the metric system the base units could be derived from a specified length (the metre) and the weight [mass] of a specified volume ( of a cubic metre) of pure water. Initially the de facto French Government of the day, the Assemblée nationale constituante, considered defining the metre as the length of a pendulum that has a period of one second at 45°N and an altitude equal to sea level. The altitude and latitude were specified to accommodate variations in gravity; the specified latitude was a compromise between the latitude of , and the median parallel of the United States (38°N) to accommodate variations.:94 However the mathematician Borda persuaded the assembly that a survey having its ends at sea level and based on a meridian that spanned at least 10% of the earth's quadrant would be more appropriate for such a basis.:96
The available technology of the 1790s made it impracticable to use these definitions as the basis of the kilogram and the metre, so prototypes that represented these quantities insofar as was practicable were manufactured. On 22 June 1799 these prototypes were adopted as the definitive reference pieces, deposited in the Archives nationales and became known as the and the . Copies were made and distributed around France.:266-269 These artefacts were replaced in 1889 by a new prototypes manufactured under international supervision. Insofar as was possible, the new prototypes were exact copies of the original prototypes, but used a later technology to ensure better stability. One of each of the kilogram and metre prototypes were chosen by lot to serve as the definitive international reference piece with the remainder being distributed to signatories of the Metre Convention. In 1889 there was no generally accepted theory regarding the nature of light but by 1960 the wavelength of specific light spectra could give a more accurate and reproducible value than a prototype metre. In that year the prototype metre was replaced by a formal definition which defines the metre in terms of the wavelength of specified light spectra. By 1983 it was accepted that the speed of light was constant and that this constant provided a more reproducible procedure for measuring length. Therefore the metre was redefined in terms of the speed of light. These definitions give a much better reproducibility and also allow anyone, anywhere with a suitably equipped laboratory, to make a standard metre.
None of the other base units rely on a prototype - all are based on phenomena that are directly observable and had been in use for many years before formally becoming part of the metric system.
The second first became a de facto base unit within the metric system when, in 1832, Carl Friedrich Gauss used it, the centimetre and the gram to express the units associated with values of absolute measurements of the Earth's magnetic field. The second, if based on the Earth's rotation, is not a constant as the Earth's rotation is slowing down—in 2008 the solar day was 0.002 s longer than in 1820. This had been known for many years; consequently in 1952 the International Astronomical Union (IAU) defined the second in terms of the Earth's rotation in the year 1900. Measurements of time were made using extrapolation from readings based on astronomy. With the launch of SI in 1960, the 11th CGPM adopted the IAU definition. In the years that followed, atomic clocks became significantly more reliable and precise and in 1968 the 13th CGPM redefined the second in terms of the frequency of a specific frequency from the emission spectrum of the caesium 133 atom, a component of atomic clocks. This provided the means to measure the time associated with astronomical phenomena rather than using astronomical phenomena as the basis from which time measurements were made.
The CGS absolute unit of electric current, the abampere, had been defined in terms of the force between two parallel current-carrying wires in 1881. In the 1940s, the International Electrotechnical Commission adopted an MKS variant of this definition for the ampere which was adopted in 1946 the CIPM.
Temperature has always been based on observable phenomena—in 1744 the degree Centigrade was based on the freezing and boiling points of water. In 1948 the CGPM adopted the Centigrade scale, renamed it the "Celsius" temperature scale name and defined it in terms of the triple point of water.
When the mole and the candela were accepted by the CGPM in 1971 and 1975 respectively, both had been defined by third parties by reference to phenomena rather than artefacts.
Each variant of the metric system has a degree of coherence—the various derived units being directly related to the base units without the need of intermediate conversion factors. For example, in a coherent system the units of force, energy and power are chosen so that the equations
hold without the introduction of constant factors. Once a set of coherent units have been defined, other relationships in physics that use those units will automatically be true. Therefore Einstein's mass-energy equation, E = mc2, does not require extraneous constants when expressed in coherent units.
The CGS system had two units of energy, the erg that was related to mechanics and the calorie that was related to thermal energy so only one of them (the erg) could bear a coherent relationship to the base units. Coherence was a design aim of SI resulting in only one unit of energy being defined - the joule.
In SI, which is a coherent system, the unit of power is the "watt" which is defined as "one joule per second". In the US customary system of measurement, which is non-coherent, the unit of power is the "horsepower" which is defined as "550 foot-pounds per second" (the pound in this context being the pound-force). Similarly, neither the US gallon nor the imperial gallon is one cubic foot or one cubic yard— the US gallon is 231 cubic inches and the imperial gallon is 277.42 cubic inches.
The concept of coherence was only introduced into the metric system in the third quarter of the nineteenth century; in its original form the metric system was non-coherent—in particular the litre was 0.001 m3 and the are (from which the hectare derives) was 100 m2. A precursor to the concept of coherence was however present in that the units of mass and length were related to each other through the physical properties of water, the gram having been designed as being the mass of one cubic centimetre of water at its freezing point.
In 1586 the Flemish mathematician Simon Stevin published a small pamphlet called De Thiende ("the tenth"). Decimal fractions had been employed for the extraction of square roots some five centuries before his time, but nobody used decimal numbers in daily life. Stevin declared that using decimals was so important that the universal introduction of decimal weights, measures and coinage was only a matter of time.
One of the earliest proposals for a decimal system in which length, area, volume and mass were linked to each other was made by John Wilkins, first secretary of the Royal Society of London in his 1668 essay "An Essay towards a Real Character and a Philosophical Language". His proposal used a pendulum that had a beat of one second as the basis of the unit of length. Two years later, in 1670, Gabriel Mouton, a French abbot and scientist, proposed a decimal system of length based on the circumference of the Earth. His suggestion was that a unit, the milliare, be defined as a minute of arc along a meridian. He then suggested a system of sub-units, dividing successively by factors of ten into the centuria, decuria, virga, virgula, decima, centesima, and millesima. His ideas attracted interest at the time, and were supported by both Jean Picard and Christiaan Huygens in 1673, and also studied at the Royal Society in London. In the same year, Gottfried Leibniz independently made proposals similar to those of Mouton.
In pre-revolutionary Europe, each state had its own system of units of measure. Some countries, such as Spain and Russia, saw the advantages of harmonising their units of measure with those of their trading partners. However, vested interests who profited from variations in units of measure opposed this. This was particularly prevalent in France where the huge inconsistency in the size of units of measure was one of the causes that, in 1789, led to the outbreak of the French Revolution.:2 During the early years of the revolution, savants including the Marquis de Condorcet, Pierre-Simon Laplace, Adrien-Marie Legendre, Antoine Lavoisier and Jean-Charles de Borda set up a Commission of Weights and Measures. The commission was of the opinion that the country should adopt a completely new system of measure based on the principles of logic and natural phenomena. Logic dictated that such a system should be based on the radix used for counting. Their report of March 1791 to the Assemblée nationale constituante considered but rejected the view of Lapace that a duodecimal system of counting should replace the existing decimal system; Lagrange taking the view such a system was bound to fail prevailed. The commission's final recommendation was that the assembly should promote a decimal based system of measurement. The leaders of the assembly accepted the views of the commission.:99-100
Initially France attempted to work with other countries towards the adoption of a common set of units of measure.:99-100 Among the supporters of such an international system of units was Thomas Jefferson who, in 1790, presented a document Plan for Establishing Uniformity in the Coinage, Weights, and Measures of the United States to congress in which he advocated a decimal system that used traditional names for units (such as ten inches per foot). The report was considered but not adopted by Congress.: 249–250
The French law of 18 Germinal, Year III (7 April 1795) defined five units of measure:
This system continued the tradition of having separate base units for geometrically related dimensions, e.g., mètre for lengths, are (100 m2) for areas, stère (1 m3) for dry capacities, and litre (1 dm3) for liquid capacities. The hectare, equal to a hundred ares, the area of a square 100 metres on a side (about 2.47 acres), is still in use. The early metric system included only a few prefixes from milli (one thousandth) to myria (ten thousand).
Originally the kilogramme, defined as being one pinte (later renamed the litre) of water at the melting point of ice, was called the grave; the gramme being an alternative name for a thousandth of a grave. However, the word grave, being a synonym for the title "count" had aristocratic connotations and was renamed the kilogramme. The name mètre was suggested by Auguste-Savinien Leblond in May 1790.: 92
France officially adopted the metric system on 10 December 1799. Although it was decreed that its use was to be mandatory in Paris that year and across the provinces the following year, the decree was not universally observed across France.
The areas that were annexed by France during the Napoleonic era inherited the metric system. In 1812 Napoleon introduced a system known as mesures usuelles which used the names of pre-metric units of measure, but defined them in terms of metric units – for example, the livre metrique (metric pound) was 500 g and the toise metrique (metric fathom) was 2 metres. After the Congress of Vienna in 1815, France lost the territories that she had annexed; some, such as the Papal States reverted to their pre-revolutionary units of measure, others such as Baden adopted a modified version of the mesures usuelles, but France kept her system of measurement intact.
In 1817 the Netherlands reintroduced the metric system, but used pre-revolutionary names—for example 1 centimetre became the duim (thumb), the ons (ounce) became 100 g and so on. Certain German states adopted similar systems and in 1852 the German Zollverein (customs union) adopted the zollpfund (customs pound) of 500 g for intrastate commerce. In 1872 the newly formed German Empire adopted the metric system as its official system of weights and measures and the newly formed Kingdom of Italy likewise, following the lead given by Piedmont, adopted the metric system in 1861.
The Exposition Universelle (1867) (Paris Exhibition) devoted a stand to the metric system and by 1875 two thirds of the European population and close on half the world's population had adopted the metric system. By 1872 the only principal European countries not to have adopted the metric system were Russia and the United Kingdom.
By 1920 countries comprising 22% of the world's population, mainly English-speaking, used the imperial system; 25% used mainly the metric system and the remaining 53% used neither.
In 1927 several million people in the United States sent over 100,000 petitions backed by the Metric Association and The General Federation of Women's Clubs urging Congress to adopt the metric system. The petition was opposed by the manufacturing industry, citing the cost of the conversion.
In 1861 a committee of the British Association for Advancement of Science (BAAS) including William Thomson (later Lord Kelvin), James Clerk Maxwell and James Prescott Joule introduced the concept of a coherent system of units based on the metre, gram and second which, in 1873, was extended to include electrical units.
On 20 May 1875 an international treaty known as the Convention du Mètre (Metre Convention) was signed by 17 states. This treaty established the following organisations to conduct international activities relating to a uniform system for measurements:
In 1881 first International Electrical Congress adopted the BAAS recommendations on electrical units, followed by a series of congresses in which further units of measure were defined and the International Electrotechnical Commission (IEC) was set up with the specific task of overseeing electrical units of measure. This was followed by the International Congress of Radiology (ISR) who, at their inaugural meeting in 1926, initiated the definition of radiological-related units of measure. In 1921 the Metre Convention was extended to cover all units of measure, not just length and mass and in 1933 the 8th CGPM resolved to work with other international bodies to agree standards for electrical units that could be related back to the international prototypes. Since 1954 the CIPM committee that oversees the definition of units of measurement, the Consultative Committee for Units, has representatives from many international organisations including the ISR, IEC and ISO under the chairmanship of the CIPM.
A number of variants of the metric system evolved, all using the Mètre des Archives and Kilogramme des Archives (or their descendants) as their base units, but differing in the definitions of the various derived units.
The centimetre gram second system of units (CGS) was the first coherent metric system, having been developed in the 1860s and promoted by Maxwell and Thomson. In 1874, this system was formally promoted by the British Association for the Advancement of Science (BAAS). The system's characteristics are that density is expressed in , force expressed in dynes and mechanical energy in ergs. Thermal energy was defined in calories, one calorie being the energy required to raise the temperature of one gram of water from 15.5 °C to 16.5 °C. The meeting also proposed two sets of units for electrical and magnetic properties - the electrostatic set of units and the electromagnetic set of units.
The CGS units of electricity were cumbersome to work with. This was remedied at the 1893 International Electrical Congress held in Chicago by defining the "international" ampere and ohm using definitions based on the metre, kilogram and second. In 1901, Giovanni Giorgi showed that by adding an electrical unit as a fourth base unit, the various anomalies in electromagnetic systems could be resolved. The metre-kilogram-second-coulomb (MKSC) and metre-kilogram-second-ampere (MKSA) systems are examples of such systems.
The International System of Units (Système international d’unités or SI) is the current international standard metric system and is also the system most widely used around the world. It is an extension of Giorgi's MKSA system—its base units are the metre, kilogram, second, ampere, kelvin, candela and mole.
The metre-tonne-second system of units (MTS) was based on the metre, tonne and second - the unit of force was the sthène and the unit of pressure was the pièze. It was invented in France for industrial use and from 1933 to 1955 was used both in France and in the Soviet Union.
Gravitational metric systems use the kilogram-force (kilopond) as a base unit of force, with mass measured in a unit known as the hyl, Technische Mass Einheit (TME), mug or metric slug. Although the CGPM passed a resolution in 1901 defining the standard value of acceleration due to gravity to be 980.665 cm/s2, gravitational units are not part of the International System of Units (SI).
The 9th CGPM met in 1948, three years after the end of the Second World War and fifteen years after the 8th CGPM. In response to formal requests made by the International Union of Pure and Applied Physics and by the French Government to establish a practical system of units of measure, the CGPM requested the CIPM to prepare recommendations for such a system, suitable for adoption by all countries adhering to the Metre Convention. The recommendation also catalogued symbols for the most important MKS and CGS units of measure and for the first time the CGPM made recommendations concerning derived units. At the same time the CGPM formally adopted a recommendation for the writing and printing of unit symbols and of numbers.
The CIPM's draft proposal, which was an extensive revision and simplification of the metric unit definitions, symbols and terminology based on the MKS system of units, was put to the 10th CGPM in 1954. In accordance with Giorgi's proposals of 1901, the CIPM also recommended that the ampere be the base unit from which electromechanical units would be derived. The definitions for the ohm and volt that had previously been in use were discarded and these units became derived units based on the metre, ampere, second and kilogram. After negotiations with the International Commission on Illumination (CIE) and IUPAP, two further base units, the degree kelvin and the candela were also proposed as base units. The full system and name "Système International d'Unités" were adopted at the 11th CGPM in October 1960. During the years that followed the definitions of the base units and particularly the mise en pratique to realise these definitions have been refined.
The formal definition of International System of Units (SI) along with the associated resolutions passed by the CGPM and the CIPM are published by the BIPM in brochure form at regular intervals. The eighth edition of the brochure Le Système International d'Unités—The International System of Units was published in 2006 and is available on the internet. In October 2011, at the 24th CGPM proposals were made to change the definitions of four of the base units. These changes should not affect the average person.
Although SI, as published by the CGPM, should, in theory, meet all the requirements of commerce, science and technology, certain units of measure have acquired such a position within the world community that it is likely they will be used for many years to come. In order that such units are used consistently around the world, the CGPM catalogued such units in Tables 6 to 9 of the SI brochure. These categories are:
The usage of the metric system varies around the world. According to the US Central Intelligence Agency's Factbook (2007), the International System of Units has been adopted as the official system of weights and measures by all nations in the world except for Burma, Liberia and the United States, while the NIST has identified the United States as the only industrialised country where the metric system is not the predominant system of units. However, reports published since 2007 hold this is no longer true of Liberia or Burma. An Agence France-Presse report from 2010 stated that Sierra Leone had passed a law to replace the imperial system with the metric system thereby aligning its system of measurement with that used by its Mano River Union (MRU) neighbours Guinea and Liberia. Reports from Burma suggest that that country is also planning to adopt the metric system.
In the United States metric units, authorised by Congress in 1866, are widely used in science, military, and partially in industry, but customary units predominate in household use. At retail stores the litre is a commonly used unit for volume, especially on bottles of beverages, and milligrams are used to denominate the amounts of medications, rather than grains. On the other hand non-metric units are used in certain regulated environments such as nautical miles and knots in international aviation.
In the countries of the Commonwealth of Nations the metric system has replaced the imperial system by varying degrees: Australia, New Zealand and Commonwealth countries in Africa are almost totally metric, India is mostly metric, Canada is partly metric while in the United Kingdom the metric system, the use of which was first permitted for trade in 1864, is used in much government business, in most industries including building, health and engineering and for pricing by measure or weight in most trading situations, both wholesale and retail. However the imperial system is often used by journalists and continues to be used in many unregulated applications.:360-366
Some other jurisdictions, such as Hong Kong, have laws mandating or permitting other systems of measurement in parallel with the metric system in some or all contexts.
The SI symbols for the metric units are intended to be identical, regardless of the language used but unit names are ordinary nouns and use the character set and follow the grammatical rules of the language concerned. For example, the SI unit symbol for kilometre is "km" everywhere in the world, even though the local language word for the unit name may vary. Language variants for the kilometre unit name include: (Italian), (German), (Dutch), (French), (Greek), (Portuguese), (Spanish) and (Russian).
Variations are also found with the spelling of unit names in countries using the same language, including differences in American English and British spelling. For example meter and liter are used in the United States whereas metre and litre are used in other English-speaking countries. In addition, the official US spelling for the rarely used SI prefix for ten is deka. In American English the term metric ton is the normal usage whereas in other varieties of English tonne is common. Gram is also sometimes spelled gramme in English-speaking countries other than the United States, though this older usage is declining.
The dual usage of or confusion between metric and non-metric units has resulted in a number of serious incidents. These include:
During its evolution, the metric system has adopted many units of measure. The introduction of SI rationalised both the way in which units of measure were defined and also the list of units in use. These are now catalogued in the official SI Brochure. The table below lists the units of measure in this catalogue and shows the conversion factors connecting them with the equivalent units that were in use on the eve of the adoption of SI.
The SI Brochure also catalogues certain non-SI units that are widely used with the SI in matters of everyday life or units that are exactly defined values in terms of SI units and are used in particular circumstances to satisfy the needs of commercial, legal, or specialised scientific interests. These units include:
After the metre was redefined in 1960, the kilogram was the only SI base unit that relied on a specific artifact. After the 1996-1998 recalibrations a clear divergence between the international and various national prototype kilograms was observed.
At the 23rd CGPM (2007), the CIPM was mandated to investigate the use of natural constants as the basis for all units of measure rather than the artifacts that were then in use. At a meeting of the CCU held in Reading, United Kingdom in September 2010, a resolution and draft changes to the SI brochure that were to be presented to the next meeting of the CIPM in October 2010 were agreed to in principle. The CCU proposed to
The CIPM meeting of October 2010 found that "the conditions set by the General Conference at its 23rd meeting have not yet been fully met. For this reason the CIPM does not propose a revision of the SI at the present time". The CIPM did however sponsor a resolution at the 24th CGPM in which the changes were agreed in principle and which were expected to be finalised at the 25th CGPM in 2014.
An ell (from Old Germanic *alinâ cognate with Latin "ulna") is a unit of measurement, originally a cubit, i.e., approximating the length of a man's arm from the elbow ("elbow" means the bend or bow of the ell or arm) to the tip of the middle finger, or about 18 inches; in later usage, any of several longer units. In English-speaking countries, these included (until the 19th century) the Flemish ell ( of a yard), English ell ( yard) and French ell ( yard), some of which are thought to derive from a 'double ell'.
Several national forms existed, with different lengths, including the Scottish ell , the Flemish ell , the French ell the Polish ell and the Danish ell
Select customs were observed by English importers of Dutch textiles: although all cloths were bought by the Flemish ell, linen was sold by the English ell, but tapestry was sold by the Flemish ell.
In England, the ell was usually 45 in (1.143 m), or a yard and a quarter. It was mainly used in the tailoring business but is now obsolete. Although the exact length was never defined in English law, standards were kept; the brass ell examined at the Exchequer by Graham in the 1740s had been in use "since the time of Queen Elizabeth".
The Viking ell was the measure from the elbow to the tip of the middle finger, about 18 inches. The Viking ell or primitive ell was used in Iceland up to the 1200s. By the 1200s a law set the "stika" as equal to 2 ells which was the English ell of the time.][
An ell-wand or ellwand was a rod of length one ell used for official measurement. Edward I of England required that every town have one. In Scotland, the Belt of Orion was called "the King's Ellwand."
The Scottish ell (Scottish Gaelic: ) was standardised in 1661, with the exemplar to be kept in the custody of Edinburgh. It comes from Middle English elle.
It was used in the popular expression -
The Ell Shop (1757) in Dunkeld, Perth and Kinross (National Trust for Scotland), is so called from the 18th century iron ell-stick attached to one corner, once used to measure cloth and other commodities in the adjacent market-place. The shaft of the old 17th century Kincardine Mercat cross stands in the square of Fettercairn, and is notched to show the measurements of an ell.
Scottish measures were made obsolete, and English measurements made standard in Scotland, by act of parliament in 1824.
The Scottish ell was equivalent to:
A fathom (abbreviation: ftm) = 6 feet or 1.8288 metres, is a unit of length in the imperial and the U.S. customary systems, used especially for measuring the depth of water.
There are two yards (6 feet) in an imperial or U.S. fathom. Originally based on the distance between a man's outstretched arms, the size of a fathom has varied slightly depending on whether it was defined as a thousandth of an (Admiralty) nautical mile or as a multiple of the imperial yard. Formerly, the term was used for any of several units of length varying around 5– feet (1.5–1.7 m).
The name derives from the Old English word fæðm, corresponding to the old Frisian word "fadem" meaning embracing arms or a pair of outstretched arms. In Middle English it was fathme. A cable length, based on the length of a ship's cable, has been variously reckoned as equal to 100 or 120 fathoms. At one time, a quarter meant one-fourth of a fathom.
Abbreviations: f, fath, fm, fth, fthm.
One fathom is equal to:
In the international yard and pound agreement of 1959 the United States, Australia, Canada, New Zealand, South Africa, and the United Kingdom defined the length of the international yard to be exactly 0.9144 metre. With the adoption of the metric SI system the use of fathoms declined.
The British Admiralty defined a fathom to be a thousandth of an imperial nautical mile (which was 6080 ft) or 6.08 feet (1.85 m). In practice the "warship fathom" of exactly 6 feet (1.8 m) was used in Britain and the United States. No conflict in the real world existed as depths on Imperial nautical charts were indicated in feet if less than 30 feet (9.1 m) and in fathoms for depths above that. Until the 19th century in England, the length of the fathom was more variable: from 5½ feet on merchant vessels to either 5 feet (1.5 m) or 7 feet (2.1 m) on fishing vessels (from 1.7 to 1.5 or 2.1 m).
Most modern nautical charts indicate depth in metres. However, the U.S. Hydrographic Office uses feet and fathoms. A nautical chart will always explicitly indicate the units of depth used.
To measure the depth of shallow waters, boatmen used a sounding line containing fathom points, some marked and others in between, called deeps, unmarked but estimated by the user. Water near the coast and not too deep to be fathomed by a hand sounding line was referred to as in soundings or on soundings. The area offshore beyond the 100 fathom line, too deep to be fathomed by a hand sounding line, was referred to as offsoundings or out of soundings. A deep-sea lead, the heaviest of sounding leads, was used in water exceeding 100 fathoms in depth.
This technique has been superseded by sonic depth finders for measuring mechanically the depth of water beneath a ship, one version of which is the Fathometer (trademark). The record made by such a device is a fathogram. A fathom line or fathom curve, a usually sinuous line on a nautical chart, joins all points having the same depth of water, thereby indicating the contour of the ocean floor.
The components of a commercial fisherman's setline were measured in fathoms. The rope called a groundline, used to form the main line of a setline, was usually provided in bundles of 300 fathoms. A single 50-fathom skein (91 mTemplate:Convert/track/disp/2) of this rope was referred to as a line. Especially in Pacific coast fisheries the setline was composed of units called skates, each consisting of several hundred fathoms of groundline, with gangions and hooks attached. A tuck seine or tuck net about 70 fathoms long (130 mTemplate:Convert/track/disp/2), and very deep in the middle, was used to take fish from a larger seine.
A line attached to a whaling harpoon was about 150 fathoms long (270 mTemplate:Convert/track/disp/2). A forerunner — a piece of cloth tied on a ship's log line some fathoms from the outboard end — marked the limit of drift line. A kite was a drag, towed under water at any depth up to about 40 fathoms, which upon striking bottom, was upset and rose to the surface.
A shot, one of the forged lengths of chain joined by shackles to form an anchor cable, was usually 15 fathoms long (27 mTemplate:Convert/track/disp/2).
In Finland, fathom (syli) is sometimes, albeit seldom, used as a maritime unit, of a nautical mile and of cable length.
It is customary][, when burying the dead, to inter the corpse at a fathom's depth, or six feet under. A burial at sea (where the body is weighted to force it to the bottom) requires a minimum of six fathoms of water. This is the origin of the phrase "to deep six" as meaning to discard, or dispose of.
Until early in the 20th century, it was the unit used to measure the depth of mines (mineral extraction) in the United Kingdom. Miners also use it as a unit of area equal to 6 square feet (0.56 m2) in the plane of a vein. In Britain, it can mean the quantity of wood in a pile of any length measuring 6 feet (1.8 m) square in cross section. In Hungary square fathom ("négyszögöl") is still in use as an unofficial measure of land area, primarily for small lots suitable for construction.
Customary units in the United States
The Union Jack, also called the Union Flag, is the national flag of the United Kingdom, as well as a flag with an official or semi-official status in some Commonwealth realms; for example, it is known by law in Canada as the Royal Union Flag. It is also used as an official flag in some of the smaller British overseas territories. The Union Jack also appears in the canton (upper left-hand quarter) of the flags of several nations and territories that were former British colonies.
The origins of the flag date back to 1603, when James VI of Scotland inherited the English and Irish thrones (as James I), thereby uniting the crowns of England, Scotland and Ireland in a personal union (which remained separate states). On 12 April 1606, a new flag to represent this regal union between England and Scotland was specified in a royal decree, according to which the flag of England (a red cross on a white background, known as St George's Cross), and the flag of Scotland (a white saltire on a blue background, known as the Saltire or St Andrew's Cross), would be joined together, forming the flag of Great Britain and first union flag.
The current design dates from a Royal Proclamation following the Union of Great Britain and Ireland in 1801. The flag combines aspects of three older national flags: the red cross of St George for England and Wales, the white saltire of St Andrew for Scotland (which two were united in the first Union Flag), and the red saltire of Saint Patrick's Flag to represent Ireland.
The terms Union Jack, Union Flag, British Flag are all historically correct for describing the de facto national flag of the United Kingdom. Whether to call it the "Union Jack" or the "Union Flag" is a matter of debate by many. According to the Flag Institute, the vexillological organisation for the United Kingdom, "the national flag of the United Kingdom, the Crown Dependencies and Overseas Territories is the Union Flag, which may also be called the Union Jack." The Institute also notes:
Nevertheless, the term "Union Flag" is used in King Charles's 1634 proclamation:
and in King George III's proclamation of 1 January 1801 concerning the arms and flag of the United Kingdom of Great Britain and Ireland:
When the first flag representing Britain was introduced on the proclamation of King James I in 1606, it became known simply as "the British flag" or "the flag of Britain". The royal proclamation gave no distinctive name to the new flag. The word "jack" was in use before 1600 to describe the maritime bow flag. By 1627 a small Union Jack was commonly flown in this position. One theory goes that for some years it would have been called just "the Jack", or "Jack flag", or "the King's Jack", but by 1674, while formally referred to as "His Majesty's Jack", it was commonly called the Union Jack, and this was officially acknowledged.
Amongst the proclamations issued by King George III at the time of the Union of 1801 was a proclamation concerning flags at sea, which referred to "Our Flags, Jacks, and Pendants" and forbade merchant vessels from wearing "Our Jack, commonly called the Union Jack" nor any pendants or colours used by the King's ships. In contrast, the King's proclamation of the same day concerning the arms and flag of the United Kingdom, not colours at sea, called the new flag "the Union Flag".][
The size and power of the Royal Navy internationally at the time could also explain why the flag was named the "Union Jack"; considering the navy was so widely utilised and renowned by the United Kingdom and colonies, it is possible that the term "Jack" occurred because of its regular use on all British ships using the "Jack Staff" (a flag pole attached to the bow of a ship). The term 'Union Jack' possibly dates from Queen Anne's time (r. 1702–14), but its origin is uncertain. It may come from the 'jack-et' of the English or Scottish soldiers, or from the name of James I who originated the first union in 1603. Even if the term "Union Jack" does derive from the jack flag, after three centuries, it is now sanctioned by use and has appeared in official use, confirmed as the national flag by Parliament and remains the popular term.
The authoritative A Complete Guide to Heraldry by Arthur Charles Fox-Davies uses the term Union Jack.
The Union Jack is normally twice as long as it is wide, a ratio of 1:2. In the United Kingdom, land flags are normally a ratio of 3:5; the Union Jack can also be made in this shape, but is 1:2 for most purposes. Flags that have the Union Jack in the canton should always be 1:2 to preserve the square fly area.][
The three component crosses that make up the Union Flag are sized as follows:
Another way of looking at it is that the white diagonal St Andrew's Cross and the red diagonal St Patrick's Cross sit side-by-side along the centre-lines of the diagonals. They each have a width of of the flag's height with a flag height fimbriation. The crosses are slightly pinwheeled with St Andrew's Cross leading in the clockwise direction.
The centre-lines of the diagonals must meet in the centre (as shown on the diagram). The three crosses retain their thickness whether they are shown with a ratio of 3:5 or 1:2
The colour specifications for the colours Union Jack (Royal) Blue, Union Flag Red and White are:
* Not official; these are Wikimedia Commons' own conversions of the Pantone.
The flag does not have reflection symmetry due to the slight pinwheeling of the St Patrick's and St Andrew's crosses, technically the counterchange of saltires. Thus, there is a right side up. Although the original specification of the Union Flag in the Royal Proclamation of 1 January 1801 did not contain a drawn pattern nor express which way the saltires should lie; they were simply "counterchanged" and the red saltire fimbriated, nevertheless, a convention was soon established which accords most closely with the description.
When statically displayed, the hoist is on the observer's left. To fly the flag correctly, the white of St Andrew is above the red of St Patrick in the upper hoist canton (the quarter at the top nearest to the flag-pole). This is expressed by the phrases wide white top and broad side up.
Interestingly, the first drawn pattern for the flag was in a parallel Proclamation of 1 January 1801 concerning civil naval ensigns, which drawing shows the red ensign (also to be used as a red jack by privateers). As it appears in the London Gazette, the broad stripe is at the top of the saltires on both sides, hoist and fly. That is not in accordance with the specification "counterchanged" as heraldry understands it.
It is often stated that a flag upside down is a form of distress signal or even a deliberate insult. In the case of the Union Jack, the difference is subtle and is easily missed by the uninformed. It is often displayed upside down inadvertently—even on commercially-made hand waving flags.
On 3 February 2009, the BBC reported that the flag had been inadvertently flown upside-down by the UK government at the signing of a trade agreement with Chinese premier Wen Jiabao. The error had been spotted by readers of the BBC news website who had contacted the BBC after seeing a photograph of the event.
In 1603, James VI of Scotland inherited the English and Irish thrones (as James I), thereby uniting the crowns of England, Scotland and Ireland in a personal union (which remained separate states). On 12 April 1606, a new flag to represent this regal union between England and Scotland was specified in a royal decree, according to which the flag of England (a red cross on a white background, known as St George's Cross), and the flag of Scotland (a white saltire on a blue background, known as the Saltire or St Andrew's Cross), would be joined together, forming the flag of Great Britain and first union flag:
This royal flag was, at first, to be used only at sea on civil and military ships of both England and Scotland, whereas land forces continued to use their respective national banners. In 1634, King Charles I restricted its use to the royal ships. After the Acts of Union 1707, the flag gained a regularised status as "the ensign armorial of the Kingdom of Great Britain", the newly created state. It was then adopted by land forces as well, although the blue field used on land-based versions more closely resembled that of the blue of the flag of Scotland.
Various shades of blue have been used in the Saltire over the years. The ground of the current Union Flag is a deep "navy" blue (Pantone 280), which can be traced to the colour used for the Blue Ensign of the Royal Navy's historic "Blue Squadron". (Dark shades of colour were used on maritime flags on the basis of durability.) In 2003 a committee of the Scottish Parliament recommended that the flag of Scotland use a lighter "royal" blue, (Pantone 300). (The Office of the Lord Lyon does not detail specific shades of colour for use in heraldry.)
A thin white stripe, or fimbriation, separates the red cross from the blue field, in accordance with heraldry's rule of tincture where colours (like red and blue) must be separated from each other by metals (like white, i.e. argent or silver). The blazon for the old union flag, to be compared with the current flag, is Azure, the Cross Saltire of St Andrew Argent surmounted by the Cross of St George Gules, fimbriated of the second.
Wales had no explicit recognition in the Union Jack as it had been a part of the Kingdom of England since being annexed by Edward I of England in 1282 and its full integration by the Laws in Wales Acts 1535–1542, and was therefore represented by the flag of England.
The Kingdom of Ireland, which had existed as a personal union with England since 1541, was likewise unrepresented in the original versions of the Union Jack. However, the flag of The Protectorate from 1658 to 1660 was inescutcheoned with the arms of Ireland. These were removed after the Restoration, supposedly because Charles II disliked them.
The original flag appears in the canton of the Commissioners' Ensign of the Northern Lighthouse Board. This is the only contemporary official representation of the pre-1801 Union Jack in the United Kingdom and can be seen flying from their George Street headquarters in Edinburgh.
This version of the Union Jack is also shown in the canton of the Grand Union Flag (also known as the Congress flag, the First Navy Ensign, the Cambridge Flag, and the Continental Colours), the first widely used flag of the United States, slowly phased out after 1777.
Lord Howe's action, or the Glorious First of June, painted in 1795, shows a Union flying from Queen CharlotteHMS on the "Glorious First of June" 1794. The actual flag, preserved in the National Maritime Museum, is a cruder approximation of the proper specifications; this was common in 18th and early 19th-century flags.
The flag is also flown beside Customs House in Loftus Street, Sydney, to mark the approximate location at which Captain Phillip first raised the Union Jack, and claimed New South Wales in 1788. On the plaque it is referred to as the "Jack of Queen Anne".
The British Army's flag is the Union Jack, but in 1938, a "British Army Non-Ceremonial Flag" was devised, featuring a Lion on crossed blades with the St Edward's Crown on a red background. This is not the equivalent of the ensigns of the other armed services, but is used at recruiting and military or sporting events, when the Army needs to be identified but the reverence and ceremony due to the regimental flags and the Union Jack would be inappropriate.
Various other designs for a common flag were drawn up following the union of the two Crowns in 1603, but were rarely, if ever, used. One version showed St George's cross with St Andrew's cross in the canton, and another version placed the two crosses side by side.
In objecting to the design of Union Flag adopted in 1606, whereby the cross of Saint George surmounted that of Saint Andrew, a group of Scots took up the matter with John Erskine, 18th Earl of Mar, and were encouraged by him to send a letter of complaint to James VI, via the Privy Council of Scotland, which stated that the flag's design "will breid some heit and miscontentment betwix your Majesties subjectis, and it is to be feirit that some inconvenientis sail fall oute betwix thame, for our seyfaring men cannot be inducit to resave that flage as it is set down". Although documents accompanying this complaint which contained drafts for alternative designs have been lost, evidence exists, at least on paper, of an unofficial Scottish variant, whereby the Scottish cross was uppermost. There is reason to think that cloth flags of this design were employed during the 17th century for unofficial use on Scottish vessels at sea. This flag's design is also described in the 1704 edition of The Present State of the Universe by John Beaumont, Junior, which contains as an appendix The Ensigns, Colours or Flags of the Ships at Sea: Belonging to The several Princes and States in the World.
On land, evidence suggesting use of this flag appears in the depiction of Edinburgh Castle by John Slezer, in his series of engravings entitled Theatrum Scotiae, c. 1693. Appearing in later editions of Theatrum Scotiae, the North East View engraving depicts the Scotch (to use the appropriate adjective of that period) version of the Union Flag flying from the Castle Clock Tower. However, it is not shown on the North Prospect of the City of Edenburgh engraving.
On 17 April 1707, just two weeks prior to the Acts of Union coming into effect, and with Sir Henry St George, Garter King of Arms, having presented several designs of flag to Queen Anne and her Privy Council for consideration, the flag for the soon to be unified Kingdom of Great Britain was chosen. At the suggestion of the Scots representatives, the designs for consideration included that version of Union Jack showing the Cross of Saint Andrew uppermost; identified as being the "Scotts union flagg as said to be used by the Scotts". However, the Queen and her Council approved Sir Henry's original effort, numbered "one".
A manuscript compiled in 1785 by William Fox and in possession of the Flag Research Center includes a full plate showing "the scoth [sic] union" flag. This could imply that there was still some insistence on a Scottish variant after the addition of the cross of St. Patrick to the Union Jack.
The current and second Union Jack dates from 1 January 1801 with the Act of Union 1800, which merged the Kingdom of Ireland and the Kingdom of Great Britain to form the United Kingdom of Great Britain and Ireland. The new design added a red saltire, the cross of Saint Patrick, for Ireland. This is counterchanged with the saltire of St Andrew, such that the white always follows the red clockwise. The arrangement has introduced a requirement to display the flag "the right way up"; see specifications for flag use, below. As with the red cross, so too the red saltire is separated by a white fimbriation from the blue field. This fimbriation is repeated for symmetry on the white portion of the saltire, which thereby appears wider than the red portion. The fimbriation of the cross of St George separates its red from the red of the saltire.
Apart from the Union Jack, Saint Patrick's cross has seldom been used to represent Ireland, and with little popular recognition or enthusiasm; it is usually considered to derive from the arms of the powerful FitzGerald family rather than any association with the saint.
The current flag's design, in use since 1801, is blazoned Azure, the Crosses Saltire of St Andrew and St Patrick, quarterly per saltire, counterchanged Argent and Gules, the latter fimbriated of the second, surmounted by the Cross of St George of the third, fimbriated as the saltire.
When the Anglo-Irish Treaty was concluded on 6 December 1921 and the creation of the new Irish Free State was an imminent prospect, the question arose as to whether the cross of Saint Patrick should remain in the Union Jack. The New York Times reported that on 22 January 1922:
There was some speculation on the matter in British dominions also, with one New Zealand paper reporting that:
However, the fact that it was likely that Northern Ireland would choose not to remain part of the Irish Free State after its foundation and remain in the United Kingdom, gave better grounds for keeping the cross of St. Patrick in the Union Jack. In this regard, Sir James Craig, the Prime Minister of Northern Ireland remarked in December 1921 that he and his government were "glad to think that our decision [to opt back into the United Kingdom] will obviate the necessity of mutilating the Union Jack." Though remaining within the United Kingdom, the new Northern Irish government dispensed with the St Patrick's Saltire in favour of a new flag derived from the coat-of-arm of the Burkes, Earls of Ulster, and quite similar to England's St George's Cross. This state-sanctioned flag was abolished in 1973 with the reintroduction of direct-rule from London over Northern Ireland.
Ultimately, when the British Home Secretary was asked on 7 December 1922 (the day after the Irish Free State was established) whether the Garter King-of-Arms was to issue any regulations with reference to the Union Jack, the response was no and the flag has never been changed.
A Dáil question in 1961 mooted raising the removal of the cross of St Patrick with the British government; Frank Aiken, the Irish Minister for External Affairs declined to "waste time on heraldic disputations".
In 2003, a private individual started a campaign – dubbed "reflag" or "Union Black" – to interpret the Union Flag in a racial context, and introduce black stripes in it. The proposal was denounced by MSP Phil Gallie as "ridiculous tokenism [that] would do nothing to stamp out racism". The campaign received little support from any quarter and is now defunct.
Since there is no uniquely Welsh element in the Union Jack, Wrexham's Labour MP Ian Lucas proposed on 27 November 2007 in a House of Commons debate that the Union Flag be combined with the Welsh flag to reflect Wales's status within the UK, and that the Red Dragon be added to the Union Flag's red, white, and blue pattern. He said the Union Jack currently only represented the other three UK nations, and Minister for Culture, Creative Industries and Tourism Margaret Hodge conceded that Mr. Lucas had raised a valid point for debate. She said "the Government is keen to make the Union Jack a positive symbol of Britishness reflecting the diversity of our country today and encouraging people to take pride in our flag". This development sparked design contests with entries from all over the world; some of the entries incorporated red dragons and even anime characters and leeks. The historical reason for no Welsh symbol in the flag is that Wales was part of the Kingdom of England when the flag was created in 1606.
The Union Jack is used as a jack by commissioned warships and submarines of the Royal Navy, such as VictoryHMS , and by commissioned Army and Royal Air Force vessels. When at anchor or alongside, it is flown from the jackstaff at the bow of the ship. When a ship is underway, the Union Jack is only flown from the jackstaff when the ship is dressed for a special occasion, such as the Queen's official birthday.
The Union Jack is worn at the masthead of a ship to indicate the presence of the Sovereign or an Admiral of the Fleet. It is also worn at the masthead of Her Majesty's Canadian ships within Canadian territorial waters on certain days of the year, such as the Queen's official birthday and Commonwealth Day. The Union Flag may also be flown from the yardarm to indicate that a court-martial is in progress, though these are now normally held at shore establishments.
No law has been passed making the Union Jack the national flag of the United Kingdom: it has become one through precedent. Its first recorded recognition as a national flag came in 1908, when it was stated in Parliament that "the Union Jack should be regarded as the National flag".][ A more categorical statement was made by the Home Secretary, Sir John Gilmour, in 1933 when he stated that "the Union Jack is the National Flag."][ But it is still officially a flag of the monarch, rather than the Union.][
Civilian use is permitted on land, but non-naval/military use at sea is prohibited. Unauthorised use of the flag in the 17th Century to avoid paying harbour duties – a privilege restricted to naval ships – caused James' successor, Charles I, to order that use of the flag on naval vessels be restricted to His Majesty's ships "upon pain of Our high displeasure."][ It remains a criminal offence under the Merchant Shipping (Registration, etc.) Act 1993 to display the Union Flag (other than the "Pilot Jack" – see below) from a British ship. Naval ships will fly the white ensign, merchant and private boats can fly the red ensign, others with special permission such as naval yacht clubs can fly the blue ensign. All of the coloured ensigns contain the union flag as part of the design.
The Court of the Lord Lyon, which has legal jurisdiction in heraldic matters in Scotland, confirms that the Union Jack "is the correct flag for all citizens and corporate bodies of the United Kingdom to fly to demonstrate their loyalty and their nationality."
The Union Jack has been in use in Canada dating back to the Scottish settlement in Nova Scotia in 1621. At the close of the Great Canadian Flag Debate of 1964, which resulted in the adoption of the Maple Leaf Flag as Canada's national flag in 1965, the Parliament of Canada voted to make the Union Flag the symbol of Canada's membership of the Commonwealth and its allegiance to the crown. The move was a concession given to conservatives who preferred to keep the old flag, with its Union Flag in the canton. The Royal Union Flag (as it is now known in Canada) is flown alongside the Maple-Leaf Flag on Commonwealth Day and other royal occasions and anniversaries. The Union Flag was also the official flag of the Dominion of Newfoundland (1931–1949) and continued after Newfoundland became a Canadian province (now Newfoundland and Labrador) until 1980.
In Australia, the current national flag gradually replaced the Union Flag. When it formally created the national flag in the Flags Act 1953, section 8 of that Act specified that "this Act does not affect the right or privilege of a person to fly the Union Jack." The Union Jack continued to be used for a period thereafter as a national flag. The current national flag of New Zealand was given official standing under the New Zealand Ensign Act in 1902, but similarly to Australia the Union Jack continued to be used in some contexts as a national flag.
On 5 February 2008, Conservative MP Andrew Rosindell introduced the 'Union Flag Bill' as a private member's bill as a 10-minute bill][ in the House of Commons. The Bill sought to formalise the position of the Union Flag as the national flag of the UK in law, to remove legal obstacles to its regular display and to officially recognise the name 'Union Jack' as having equal status with 'Union Flag'. However the Bill did not receive its second reading by the end of that parliamentary session.
Although the most common ratio is 1:2, other ratios exist. The Royal Navy's flag code book, BR20 Flags of All Nations, states that both 1:2 and 3:5 versions are official. The 3:5 version is most commonly used by the British Army and is sometimes known as the War flag. In this version the innermost points of the lower left and upper right diagonals of the St Patrick's cross are cut off or truncated.
The Queen's Harbour Master's flag, like the Pilot Jack, is a 1:2 flag that contains a white-bordered Union Flag that is longer than 1:2. The jacks of ships flying variants of the Blue Ensign are square and have a square Union Flag in the canton. The Queen's Colours of Army regiments are 36 by 43 inches (910 mm × 1,100 mm); on them, the bars of the cross and saltire are of equal width; so are their respective fimbriations, which are very narrow.
The Union Flag was found in the canton (upper left-hand quarter) of the flags of many colonies of Britain, while the field (background) of their flags was the colour of the naval ensign flown by the particular Royal Navy squadron that patrolled that region of the world. Nations and colonies that have used the Union Flag at some stage have included Aden, Barbados, Borneo, Burma, Canada, Ceylon, Cyprus, British East Africa (Kenya Colony), Gambia, Gold Coast (Ghana), Hong Kong, Jamaica, Lagos, Malta, Mauritius, Nigeria, Palestine, Penang (Malaysia), Rhodesia, Sierra Leone, Singapore, Somaliland, South Asia (SAARC), Tanganyika, Trinidad, Uganda, and the United States. As former British Empire nations were granted independence, these and other versions of the Union Flag were decommissioned. The most recent decommissioning of the Union Flag came on 1 July 1997, when the former Dependent Territory of Hong Kong was handed over to the People's Republic of China.
All administrative regions and territories of the United Kingdom fly the Union Jack in some form, with the exception of Gibraltar (other than the government ensign) and the Crown Dependencies. Outside the UK, the Union Jack is usually part of a special ensign in which it is placed in the upper left hand corner of a blue field, with a signifying crest in the bottom right.
Four former British colonies in Oceania which are now independent countries incorporate the Union Jack as part of their national flags: Australia, New Zealand, Tuvalu and Fiji, the last of which is not part of the Commonwealth realms.
In former British colonies, the Union Jack was used semi-interchangeably with territorial flags for significant parts of their early history. This was the case in Canada until the introduction of the Maple Leaf Flag in 1965, but it is still used in the flags of a number of Canadian provinces such as British Columbia, Manitoba and Ontario. Newfoundland and Labrador uses a modified version of the Union Flag, once the flag of the province. Canadian practice allows the flag, known in Canada as the Royal Union Flag, to be flown by private individuals and government agencies to show support for the Monarch and the Commonwealth. On some official occasions, the flag is always flown besides the Maple Leaf Flag, one such occasion is on the anniversary of the Statute of Westminster.
Many Australian flags retain the use of the Union Jack, including the Royal Australian Navy Ensign (also known as the Australian White Ensign), the Royal Australian Air Force Ensign, the Australian Red Ensign (for use by merchant and private vessels) and the Australian Civil Aviation Ensign. The flags of all six Australian States retain the Union Jack in the canton, as do some regional flags such as the Upper and Lower Murray River Flags. The Vice-Regal flags of the State Governors also retain the use of the Union Jack.
The Basque Country's flag, the Ikurriña, is also loosely based on the Union Jack, reflecting the significant commercial ties between Bilbao and Britain at the time the Ikurriña was designed in 1894. The Miskito people sometimes use a similar flag that also incorporates the Union Jack in its canton, due to long periods of contact in the Mosquito Coast.
The Union Jack was used by the United States in its first flag, the Grand Union Flag. This flag was of a similar design to the one used by the British East India Company. Hawaii, a state of the United States but located in Oceania, incorporates the Union Jack in its state flag. According to one story, the King of Hawaii asked the British mariner, George Vancouver, during a stop in Lahaina, what the piece of cloth flying from his ship was. Vancouver replied that it represented his king's authority. The Hawaiian king then adopted and flew the flag as a symbol of his own royal authority not recognising its national derivation. Hawaii's flag represents the only current use of the Union Jack in any American state flag.
Also in the United States, the Union Flag of 1606 is incorporated into the flag of Baton Rouge, the capital city of Louisiana. Baton Rouge was a British colony from the time of the Seven Years' War until the end of the American Revolutionary War, when it was captured by Spanish and American forces. Symbols from the colonial powers France and Spain are also incorporated into the Baton Rouge flag. Taunton, Massachusetts, USA, has in recent years][ used a flag with the old style Union Flag. Likewise, Westmoreland County, Pennsylvania, has been known to fly a flag containing the King's Colours since 1973.
The Union Jack also appeared on both the 1910–1928 and 1928–1994 flags of South Africa. The 1910–1928 flag was a red ensign with the Union coat of arms in the fly. The 1928–1994 flag, based on the Prinsenvlag and commonly known as the oranje-blanje-blou (orange-white-blue), contained the Union Jack as part of a central motif at par with the flags of the two Boer republics of the Orange Free State and Transvaal. To keep any one of the three flags from having precedence, the Union Jack is spread horizontally from the Orange Free State flag towards the hoist; closest to the hoist, it is in the superior position but since it is reversed it does not precede the other flags.
The coat of arms of the Chilean city of Coquimbo features the Union Jack, owing to its historical commercial links to Britain.
The Union Flag can be found in the canton of several of the ensigns flown by vessels and aircraft of the United Kingdom and its overseas territories. These are used in cases where it is illegal to fly the Union Flag, such as at sea from a ship other than a British warship. Normal practice for UK ships is to fly the White ensign (Royal Navy) or the Red ensign (Merchant and private boats). Similar ensigns are used by other countries (such as New Zealand and Australia) with the Union Flag in the canton. Other countries (such as India and Jamaica) follow similar ensign etiquette as the UK, replacing the Union Flag with their own national flag.
The flag in a white border occasionally seen on merchant ships was sometimes referred to as the Pilot Jack. It can be traced back to 1823 when it was created as a signal flag, never intended as a civil jack. A book][ issued to British consuls in 1855 states that the white bordered Union Flag is to be hoisted for a pilot. Although there was some ambiguity regarding the legality of it being flown for any other purpose on civilian vessels, its use as an ensign or jack was established well in advance of the 1864 Act that designated the Red Ensign for merchant shipping. In 1970, the white-bordered Union Flag ceased to be the signal for a pilot, but references to it as national colours were not removed from the current Merchant Shipping Act and it was legally interpreted as a flag that could be flown on a merchant ship, as a jack if desired. This status was confirmed to an extent by the Merchant Shipping (Registration, etc.) Act 1993 and the consolidating Merchant Shipping Act 1995 which, in Section 4, Subsection 1, prohibits the use of any distinctive national colours or those used or resembling flags or pendants on Her Majesty's Ships, "except the Red Ensign, the Union flag (commonly known as the Union Jack) with a white border", and some other exceptions permitted elsewhere in the Acts. However, Section 2 regards the 'British flag', and states that "The flag which every British ship is entitled to fly is the Red Ensign (without any defacement or modification) and, subject to (a warrant from Her Majesty or from the Secretary of State, or an Order of Council from her Majesty regarding a defaced Red Ensign), no other colours." The ultimate determination of legality, however, is that many civil vessels routinely fly the white bordered Union Flag without official opposition, making it the de facto Civil Jack.][
The Hudson's Bay Company was one of a few non-government institutions using the Union Jack in part of the flag. HBC rival North West Company had a similar flag as well. The HBC jack is no longer in use and replaced with a corporate flag featuring the company's coat of arms.
In July 2007, the British prime minister at the time, Gordon Brown, unveiled plans to have the Union Flag flown more often from government buildings. While consultation on new guidelines is under way, the decision to fly the flag may be made by each government department.][
Previously the flag was generally only flown on public buildings on days marking the birthdays of members of the Royal Family, the wedding anniversary of the monarch, Commonwealth Day, Accession Day, Coronation Day, the Queen's Official Birthday, Remembrance Sunday and on the days of the State Opening and prorogation of Parliament. The Union Flag is flown at half mast from the announcement of the death of the Sovereign (save for Proclamation Day), or upon command of the Sovereign.
The current flag days where the Union Flag should be flown from government buildings throughout the UK are:
In addition, the Union Flag should be flown in the following areas on specified days:
On 30 November, (St Andrew's Day), the Union Flag can be flown in Scotland only where a building has more than one flagpole—on this day the Saltire will not be lowered to make way for the Union Flag if there is only one flagpole. This difference arose after Members of the Scottish Parliament complained that Scotland was the only country in the world that could not fly its national flag on its national day. However, on 23 April, St George's Day, it is the Union Flag of the United Kingdom that is flown over United Kingdom's government offices in England.
Non-government organisations may fly the Union Flag whenever they choose.
In Canada, the Royal Union Flag is flown from federal buildings, airports, warships, military bases, and other government buildings on the following days:
The flag is only flown in addition to the Canadian national flag, where physical arrangements allow (e.g., when there is more than one flag pole).
In general, there are no prescriptions regarding the use and disposal of the flag in a manner akin to the United States Flag Code. This reflects its largely unofficial status as a national flag. There is no contemporary national concept of flag desecration. There is also no specific way in which the Union Flag should be folded as there is with the United States Flag. It should simply be folded ready for the next use.
Royal Navy Stores Duties Instructions, article 447, dated 26 February 1914, specified that flags condemned from further service use were to be torn up into small pieces and disposed of as rags (ADM 1/8369/56), not to be used for decoration or sold. The exception was flags that had flown in action: these could be framed and kept on board, or transferred to a "suitable place", such as a museum (ADM 1/8567/245).
Commonly the Union Flag is used on computer software and Internet pages as an icon representing a choice of the English language where a choice among multiple languages may be presented to the user. The Union flag has been embroidered on various Reebok equipment as a mark of the brand's British origin, and the Reebok Union Jack has been referred to as a brand icon. Many music artists have used the Union flag ranging from rock artists The Who, Freddie Mercury, Morrissey, Oasis, Iron Maiden and Def Leppard, to the pop girl group the Spice Girls.
United States customary units are a system of measurements commonly used in the United States. The U.S. customary system developed from English units which were in use in the British Empire before American independence. Consequently most U.S. units are virtually identical to the British imperial units. However, the British system was overhauled in 1824, changing the definitions of some units used there, so several differences exist between the two systems.
The majority of U.S. customary units were redefined in terms of the meter and the kilogram with the Mendenhall Order of 1893, and in practice, for many years before. These definitions were refined by the international yard and pound agreement of 1959. The U.S. primarily uses customary units in its commercial activities, while science, medicine, government, and many sectors of industry use metric units. The SI metric system, or International System of Units is preferred for many uses by NIST
The system of imperial units or the imperial system (also known as British Imperial) is the system of units first defined in the British Weights and Measures Act of 1824, which was later refined and reduced. The system came into official use across the British Empire. By the late 20th century, most nations of the former empire had officially adopted the metric system as their main system of measurement, but some Imperial units are still used in the United Kingdom and Canada.