"1 sea mile"", followed by ""For most practical purposes distance is measured from the latitude scale, assuming that one minute of latitude equals one nautical mile"". One tenth of a nautical mile is a cable length. The derived unit of speed is the knot, defined as one nautical mile per hour. The metre was originally defined as of the meridian arc from the North pole to the equator passing through Dunkirk. The Earth’s circumference is therefore approximately 40,000 km. The equatorial circumference is slightly longer than the polar circumference – the measurement based on this (40,075.017 km x x ="
"Nautical mile A nautical mile (also known as an air mile) is a unit of measurement defined as exactly . Historically, it was defined as one minute of latitude, which is one sixtieth of a degree of latitude – i.e. since a minute of a degree is x = , the Earth's polar circumference is approximately 21,600 nautical miles. It is a non-SI unit which today has a continued use in both air and marine navigation, and for the definition of territorial waters. There is no single internationally agreed symbol. While using M itself, the International Bureau of Weights and"
") is known as the geographical mile. Nautical mile A nautical mile (also known as an air mile) is a unit of measurement defined as exactly . Historically, it was defined as one minute of latitude, which is one sixtieth of a degree of latitude – i.e. since a minute of a degree is x = , the Earth's polar circumference is approximately 21,600 nautical miles. It is a non-SI unit which today has a continued use in both air and marine navigation, and for the definition of territorial waters. There is no single internationally agreed symbol. While using M"
"In the United States, the nautical mile was defined in the 19th century as 6,080.2 feet (1,853.249 m), whereas in the United Kingdom, the ""Admiralty nautical mile"" was defined as 6,080 feet (1,853.184 m) and was about one minute of latitude in the latitudes of the south of the UK. Other nations had different definitions of the nautical mile, but it is now internationally defined to be exactly . The nautical mile per hour is known as the knot. Nautical miles and knots are almost universally used for aeronautical and maritime navigation, because of their relationship with degrees and minutes"
"United States Navy a premiere foot race to replace the disestablished Blue Angels Marathon. The length of ten nautical miles was chosen as the length because it is roughly the distance from the shore to the horizon when viewed at sea level. It was also the distance traveled by the Allied Forces on D-Day, significant because the inaugural run of the Navy Ten Nautical Miler took place on June 6, 2010, the anniversary of D-Day. A nautical mile is approximately the distance of one minute of arc of latitude on the Earth's surface. Sailors throughout history have used this form"
"still use US customary units despite many years of informal or optional metrication. At least two states, Kentucky and California, have even moved towards demetrication of highway construction projects. Air and sea transportation commonly use the nautical mile. This is about one minute of arc of latitude along any meridian arc and it is precisely defined as 1852 metres (about 1.151 statute miles). It is not an SI unit (although it is accepted for use in the SI by the BIPM). The prime unit of speed or velocity for maritime and air navigation remains the knot (nautical mile per hour)."
"one minute of arc along a meridian of a spherical earth. An ellipsoid model leads to a variation of the nautical mile with latitude. This was resolved by defining the nautical mile to be exactly 1,852 metres. However for all practical purposes distances are measured from the latitude scale of charts. As the Royal Yachting Association says in its manual for day skippers: ""1 (minute) of Latitude = 1 sea mile"", followed by ""For most practical purposes distance is measured from the latitude scale, assuming that one minute of latitude equals one nautical mile"". There are six auxiliary latitudes that"
"latitude could be used as the basis for a unit of measurement for distance and proposed the nautical mile as one minute or one-sixtieth () of one degree of latitude. As one degree is of a circle, one minute of arc is of a circle (or, in radians, ). These sexagesimal (base 60) units originated in Babylonian astronomy. Gunter used Snell's circumference to define a nautical mile as 6,080 feet, the length of one minute of arc at 48 degrees latitude. Since the earth is not a perfect sphere but is an oblate spheroid with slightly flattened poles, a minute"
"of latitude is not constant, but about at the poles and at the Equator, with a mean value of . Other countries measure the minute of arc at 45 degrees latitude, giving the nautical mile a length of . In 1929, the international nautical mile was defined by the First International Extraordinary Hydrographic Conference in Monaco as precisely 1,852 metres. Imperial units and United States customary units used a definition of the nautical mile based on the Clarke (1866) Spheroid. The United States nautical mile was defined as based in the Mendenhall Order foot of 1893. It was abandoned in"
"determine latitude at sea. He reasoned that the lines of latitude could be used as the basis for a unit of measurement for distance and proposed the nautical mile as one minute or one-sixtieth () of one degree of latitude. As one degree is of a circle, one minute of arc is of a circle – such that the polar circumference of the Earth would be exactly 21,600 miles. Gunter used Snell's circumference to define a nautical mile as 6,080 feet, the length of one minute of arc at 48 degrees latitude. In 1791, the French Academy of Sciences selected"
"Navy Ten Nautical Miler The Navy Ten Nautical Miler (Navy 10 nm, 11.5 mi) is a run held at Naval Support Activity Mid-South in Millington, Tennessee. It is unique because it is the only race measured in nautical miles as opposed to statute miles. The Navy Ten Nautical Miler is an event officially sanctioned by USA Track & Field, the national governing body for track and field, long-distance running, and race walking in the United States. The event is coordinated in association with the Memphis Runners Track Club. The Navy Ten Nautical Miler was founded in 2010 to give the"
"accurate because they measure angles from the horizon, eliminating errors caused by the placement of an instrument's pointers, and because their dual mirror system cancels relative motions of the instrument, showing a steady view of the object and horizon. Navigators measure distance on the globe in degrees, arcminutes and arcseconds. A nautical mile is defined as 1852 meters, but is also (not accidentally) one minute of angle along a meridian on the Earth. Sextants can be read accurately to within 0.2 arcminutes, so the observer's position can be determined within (theoretically) 0.2 miles, about 400 yards (370 m). Most ocean"
"nautical mile, reflect off a target, and return to the radar antenna. Since a nautical mile is defined as 1,852 m, then dividing this distance by the speed of light (299,792,458 m/s), and then multiplying the result by 2 yields a result of 12.36 μs in duration. Another form of distance measuring radar is based on frequency modulation. Frequency comparison between two signals is considerably more accurate, even with older electronics, than timing the signal. By measuring the frequency of the returned signal and comparing that with the original, the difference can be easily measured. This technique can be used"
"Using official modern definitions, one nautical mile is exactly 1.852 kilometres, which implies that 1 kilometre is about nautical miles. This modern ratio differs from the one calculated from the original definitions by less than one part in 10,000. For much of the history of mathematics, even the greatest thinkers considered it impossible to compute the length of an irregular arc. Although Archimedes had pioneered a way of finding the area beneath a curve with his ""method of exhaustion"", few believed it was even possible for curves to have definite lengths, as do straight lines. The first ground was broken"
"latitude is 1 nautical mile. The example above would be given as 40° 11.25′ (commonly written as 11′25 or 11′.25). The older system of thirds, fourths, etc., which continues the sexagesimal unit subdivision, was used by al-Kashi and other ancient astronomers, but is rarely used today. These subdivisions were denoted by writing the Roman numeral for the number of sixtieths in superscript: 1 for a ""prime"" (minute of arc), 1 for a second, 1 for a third, 1 for a fourth, etc. Hence the modern symbols for the minute and second of arc, and the word ""second"" also refer to"
"Thousandth of an inch A thousandth of an inch is a derived unit of length in an inch-based system of units. Equal to of an inch, it is normally referred to as a thou , a thousandth, or (particularly in the United States) a mil. The plural of ""thou"" is also ""thou"" (thus one hundredth of an inch is ""10 thou""), while the plural of ""mil"" is ""mils"" (thus ""10 mils""). The words are shortened forms of the English and Latin words for ""thousand"" (""mille""). The US customary ""mil"" can be confused with the millimetre, which is the standard meaning"
"favour of the international nautical mile in 1954. The Imperial nautical mile, often called an Admiralty mile, or more correctly, an Admiralty measured mile, was defined by its relation to the Admiralty knot, 6,080 imperial feet per hour, so 1 imperial nautical mile is about 1,853.181 metres. It was abandoned in 1970 and, legally, references to the obsolete unit are now converted to 1,853 metres. Despite the existence of precise modern definitions, in the early 21st century the old definitions are still in use. The Royal Yachting Association says in its manual for day skippers: ""1 (minute) of Latitude ="
"not knotted and sailors measured the length directly on the line. With the introduction of the nautical mile as a standard unit of measure at sea in the 15th century, they began to mark the line at equal intervals proportional to the nautical mile and to the time interval used for measurement. Initially, the markings were simply knots in the line. Later, sailors worked knotted cords into the log-line. Many ships used knots spaced 8 fathoms (48 feet or 14.6 meters) apart, while other ships used the 7-fathom prescription. The time interval needs to be adjusted according to the distance"
"ten thousand kilometres), was determined in the late 20th century by space satellites to be 10,002,290 meters. This small error of 2,290 meters equals 1.423 statute miles; the error in such a large measurement amounts to 14½ inches per statute mile. It represents in each meter an error of approximately 0.23 millimetres – slightly more than the width of a single strand of human hair. This discrepancy is sometimes mentioned as ""Méchain's error"", with the suggestion that the tiny variation in the length of the meridian (not detected for nearly two hundred years) can be attributed to Méchain's calculations. But"
"than approximately 1/80,000. Mariners generally use the nautical mile, which, because a nautical mile is approximately equal to a minute of latitude, can be measured against the latitude scale at the sides of the chart. While linear scales are used on architectural and engineering drawings, particularly those that are drawn after the subject has been built, many such drawings do not have a linear scale and are marked ""Do Not Scale Drawing"" in recognition of the fact that paper size changes with environmental changes and only dimensions that are specifically shown on the drawing can be used reliably in precise"
"longitude at the equator is thus exactly 60 geographical miles. It was closely related to the nautical mile, which was originally determined as 1 minute of arc along a great circle of the Earth, but is nowadays defined as exactly 1852 metres. The US National Institute of Standards and Technology (NIST) notes that: ""The international nautical mile of 1 852 meters (6 076.115 49...feet) was adopted effective July 1, 1954, for use in the United States. The value formerly used in the United States was 6 080.20 feet = 1 nautical (geographical or sea) mile."" (6080.2 feet is 1853.24496 meters.)"
"A separate reference identifies the geographic mile as being identical to the international nautical mile of 1852 metres (and slightly shorter than the British nautical mile of 6 080 feet, equivalent to 1853.184 meters). The unit is not used much, but is cited in some United States laws (e.g., Section 1301(a) of the Submerged Lands Act, which defines state seaward boundaries in terms of geographic miles). While debating what became the Land Ordinance of 1785, Thomas Jefferson's committee wanted to divide the public lands in the west into ""hundreds of ten geographical miles square, each mile containing 6086 and 4-10ths"
"(equivalent to 914.4 m), depth as ""feet"", and velocity, in some cases, as ""feet per second"". The Navy and Air Force continue to measure distance in nautical miles and speed in knots; these units are now accepted for use with SI by the BIPM. Furthermore, in military aviation NATO countries use feet for flight heights, as they do in the civilian aviation. Illegal drugs and controlled substances are often measured in metric quantities. The federal law prohibiting them defines the penalties in metric masses. In everyday use within its subculture, marijuana is sold using a combination of metric and American"
"this section lists lengths starting at 10 m (1 Mm or 1,000 km). 1 megametre is equal to: To help compare different orders of magnitude, this section lists lengths starting at 10 metres (10 megametres or 10,000 kilometres). 10 megametres (10 Mm) is To help compare different orders of magnitude, this section lists lengths starting at 10 metres (100 megametres or 100,000 kilometres or 62,150 miles). To help compare different distances this section lists lengths starting at 10 metres (1 gigametre (Gm) or 1 billion metres). To help compare different distances this section lists lengths starting at 10 metres (10"
"the ellipsoid varies with latitude, being the longest at the pole and the shortest at the equator as is the nautical mile. A metre was originally defined as the 10-millionth part of the length from equator to North Pole along the meridian through Paris (the target was not quite reached in actual implementation, so that is off by 200 ppm in the current definitions). This means that one kilometre is roughly equal to (1/40,000) * 360 * 60 meridional minutes of arc, which equals 0.54 nautical mile, though this is not exact because the two units are defined on different"
"scale, of the sort on many maps, would therefore be useless on such a chart. Since the length of a nautical mile, for practical purposes, is equivalent to about a minute of latitude, a distance in nautical miles on a chart can easily be measured by using dividers and the latitude scales on the sides of the chart. Recent British Admiralty charts have a latitude scale down the middle to make this even easier. Speed is sometimes incorrectly expressed as ""knots per hour"", which would mean ""nautical miles per hour per hour"" and thus would refer to acceleration. Prior to"
"metric measures, and describe the ""direction"" of the local normal to the reference ellipsoid of revolution. This is ""approximately"" the same as the direction of the plumbline, i.e., local gravity, which is also the normal to the geoid surface. For this reason, astronomical position determination – measuring the direction of the plumbline by astronomical means – works fairly well provided an ellipsoidal model of the figure of the Earth is used. One geographical mile, defined as one minute of arc on the equator, equals 1,855.32571922 m. One nautical mile is one minute of astronomical latitude. The radius of curvature of"
"hour. Etymologically, the term derives from counting the number of knots in the line that unspooled from the reel of a chip log in a specific time. is the length of the internationally agreed nautical mile. The US adopted the international definition in 1954, having previously used the US nautical mile (). The UK adopted the international nautical mile definition in 1970, having previously used the UK Admiralty nautical mile ( or ). The speeds of vessels relative to the fluids in which they travel (boat speeds and air speeds) are measured in knots. For consistency, the speeds of navigational"
"Measures recognises that NM, Nm and nmi are also in use. The word mile is from the Latin word for a thousand paces: mille passus. Navigation at sea was done by eye until around 1500 when navigational instruments were developed and cartographers began using a coordinate system with parallels of latitude and meridians of longitude. In 1617 the Dutch scientist Willebrord Snell assessed the circumference of the Earth at 24,630 Roman miles (24,024 statute miles). Around that time British mathematician Edmund Gunter improved navigational tools including a new quadrant to determine latitude at sea. He reasoned that the lines of"
"length (inch, foot, yard and international mile) were the same in the US, though the US rarely uses some of the intermediate units, such as the (surveyor's) chain (22 yards) and the furlong (220 yards). At one time the definition of the nautical mile was based on the sphere whose surface is the same as the Clarke Ellipsoid. In the US, the full value of 1853.256 metres was used, but in the Commonwealth, this was rounded to 6080 feet (1853.184 m). These have been replaced by the international version, which rounds the sixtieth part of the 45° to the nearest"
"help compare different orders of magnitude, this section lists lengths between 10 m and 10 m (100 μm and 1 mm). The term ""Myriometre"" (abbr. mom, equivalent to 100 micrometers; frequently confused with the ""Myriametre"", 10 kilometers) is deprecated; the decimal metric prefix myrio- is obsolete and not included among the prefixes when the International System of Units was introduced in 1960. To help compare different orders of magnitude this section lists lengths between 10 m and 10 m (1 mm and 1 cm). To help compare different orders of magnitude this section lists lengths between 10 m and 10"
"To compare different orders of magnitude this section lists lengths between 100 metres and 1000 metres (1 kilometre). 100 metres (sometimes termed a hectometre) is equal to: To help compare different orders of magnitude this section lists lengths between 1 kilometre and 10 kilometres (10 and 10 metres). 1 kilometre (unit symbol km) is equal to: To help compare different orders of magnitude this section lists lengths between 10 and 100 kilometres (10 to 10 metres). The ""myriametre"" (sometimes also spelled ""myriameter"", ""myriometre"" and ""myriometer"") (10,000 metres) is a deprecated unit name; the decimal metric prefix myria- (sometimes also written"
"per knot. Although the unit ""knot"" does not fit within the SI system, its retention for nautical and aviation use is important because the length of a nautical mile, upon which the knot is based, is closely related to the size of the Earth. As a result, nautical miles and knots are convenient units to use when navigating an aircraft or ship. Standard nautical charts are on the Mercator projection and the horizontal (East-West) scale varies with latitude. On a chart of the North Atlantic, the scale varies by a factor of two from Florida to Greenland. A single graphic"