An ell is a unit of measurement a cubit, i.e. approximating the length of a man's arm from the elbow to the tip of the middle finger, or about 18 inches. In English-speaking countries, these included the Flemish ell, English ell and French ell, some of which are thought to derive from a "double ell". An ell-wand or ellwand was a rod of length one ell used for official measurement. Edward I of England required. In Scotland, the Belt of Orion was called "the King's Ellwand". Several national forms existed, with different lengths, including the Scottish ell, the Flemish ell, the French ell, the Polish ell, the Danish alen, the Swedish aln and the German ell of different lengths in Frankfurt, Leipzig or Hamburg. 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; the Viking ell was the measure from the elbow to the tip of about 18 inches. The Viking ell or primitive ell was used in Iceland up to the 13th century.
By the 13th century, a law set the "stika" as equal to 2 ells, the English ell of the time. In England, the ell was 45 in, or a yard and a quarter, it was used in the tailoring business but is now obsolete. Although the exact length was never defined in English law, standards were kept; the Scottish ell is 37 inches, just over twice an ell. The Scottish ell was standardised with the exemplar to be kept in the custody of Edinburgh, it comes from Middle English elle. It was used in the popular expression "Gie'im an inch, an he'll tak an ell"; the Ell Shop in Dunkeld and Kinross, 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 17th-century Kincardine mercat cross stands in the square of Fettercairn, is notched to show the measurements of an ell. Scottish measures were made obsolete, English measurements made standard in Scotland, by act of parliament in 1824; the Scottish ell was equivalent to: Scottish measures: 3 1⁄12 feet Metric system: 94.1318 cm Imperial system: 1.03 international yards, approx.
37.1 inches Ells are used for measuring the length of rope in J. R. R. Tolkien's The Lord of the Rings. In the epic poem Sir Gwaine and the Green Knight, the Green Knight's axe head was an ell wide; this article incorporates text from "Dwelly's Gaelic Dictionary". Collins Encyclopedia of Scotland Scottish National Dictionary and Dictionary of the Older Scottish Tongue Weights and Measures, by D. Richard Torrance, SAFHS, Edinburgh, 1996, ISBN 1-874722-09-9
The Carcel lamp was an efficient lighting device used in the nineteenth century for domestic purposes and in France as the standard measure for illumination. The lamp was invented by the French watchmaker Bernard Guillaume Carcel to overcome the disadvantages of the Argand-type lamps in use; the vegetable - colza - oils available were thick and would not travel far up a wick. The Argand lamps used a gravity feed which meant that the oil reservoir was located above the burner, casting a shadow and making the lamp top heavy. Carcel designed a lamp with the oil reservoir in the body of the lamp. To keep the oil moving up to the burner, Carcel housed a clockwork mechanism in the lamp base that drove a small pump submerged in the oil tank; the winding key was located at the bottom of the lamp base. Another innovative feature was that fuel was pumped into the wick tubes at a greater volume than was necessary for burning so that it overflowed the top of the wicks, thus cooling the burner; the advantages Carcel claimed for his lamp in his 1800 patent in Paris were that the movement operated unattended, the oil could be used to the last drop, the lamp would stay lit for sixteen hours continuously without refilling, it provided illumination for several persons at the same time with a single burner.
They were complex devices however, were expensive and prone to problems in the mechanism. They were most popular in wealthier European cities, their unpopularity was due to the necessity of having to return them to the manufacturers for repair. In 1829 the simpler Moderator lamp was invented, which dispensed with clockwork and used only a weighted piston to move the oil, this superseded them; the French physical standard Carcel lamp consisted of a cylindrical Argand burner, gave the standard brightness when 42 grammes of colza oil were consumed per hour. The supply and draught were regulated by clockwork. Edith Wharton, in her novel Ethan Frome, describes the "best parlour" as being'weakly illuminated by a gurgling Carcel lamp'. Giuseppi Tomasi di Lampedusa, in the first chapter of his novel ’’The Leopard’’, describes a dinner lit by ‘a powerful carcel-lamp hung precariously under the Murano chandelier.’ List of obsolete units of measurement
In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is an SI base unit. Photometry deals with the measurement of visible light; the human eye can only see light in the visible spectrum and has different sensitivities to light of different wavelengths within the spectrum. When adapted for bright conditions, the eye is most sensitive to greenish-yellow light at 555 nm. Light with the same radiant intensity at other wavelengths has a lower luminous intensity; the curve which measures the response of the human eye to light is a defined standard, known as the luminosity function. This curve, denoted V or y ¯, is based on an average of differing experimental data from scientists using different measurement techniques. For instance, the measured responses of the eye to violet light varied by a factor of ten.
Luminous intensity should not be confused with another photometric unit, luminous flux, the total perceived power emitted in all directions. Luminous intensity is the perceived power per unit solid angle. If a lamp has a 1 lumen bulb and the optics of the lamp are set up to focus the light evenly into a 1 steradian beam the beam would have a luminous intensity of 1 candela. If the optics were changed to concentrate the beam into 1/2 steradian the source would have a luminous intensity of 2 candela; the resulting beam is brighter, though its luminous flux remains unchanged. Luminous intensity is not the same as the radiant intensity, the corresponding objective physical quantity used in the measurement science of radiometry. Like other SI base units, the candela has an operational definition—it is defined by the description of a physical process that will produce one candela of luminous intensity. By definition, if one constructs a light source that emits monochromatic green light with a frequency of 540 THz, that has a radiant intensity of 1/683 watts per steradian in a given direction, that light source will emit one candela in the specified direction.
The frequency of light used in the definition corresponds to a wavelength in a vacuum of 555 nm, near the peak of the eye's response to light. If the source emitted uniformly in all directions, the total radiant flux would be about 18.40 mW, since there are 4π steradians in a sphere. A typical candle produces roughly one candela of luminous intensity. Prior to the definition of the candela, a variety of units for luminous intensity were used in various countries; these were based on the brightness of the flame from a "standard candle" of defined composition, or the brightness of an incandescent filament of specific design. One of the best-known of these standards was the English standard: candlepower. One candlepower was the light produced by a pure spermaceti candle weighing one sixth of a pound and burning at a rate of 120 grains per hour. Germany and Scandinavia used the Hefnerkerze, a unit based on the output of a Hefner lamp. In 1881, Jules Violle proposed the Violle as a unit of luminous intensity, it was notable as the first unit of light intensity that did not depend on the properties of a particular lamp.
All of these units were superseded by the definition of the candela. The luminous intensity for monochromatic light of a particular wavelength λ is given by I v = 683 ⋅ y ¯ ⋅ I e, where Iv is the luminous intensity in candelas, Ie is the radiant intensity in watts per steradian, y ¯ is the standard luminosity function. If more than one wavelength is present, one must sum or integrate over the spectrum of wavelengths present to get the luminous intensity: I v = 683 ∫ 0 ∞ y ¯ ⋅ d I e d λ d λ. Brightness International System of Quantities Radiance
Mining is the extraction of valuable minerals or other geological materials from the earth from an ore body, vein, reef or placer deposit. These deposits form a mineralized package, of economic interest to the miner. Ores recovered by mining include metals, oil shale, limestone, dimension stone, rock salt, potash and clay. Mining is required to obtain any material that cannot be grown through agricultural processes, or feasibly created artificially in a laboratory or factory. Mining in a wider sense includes extraction of any non-renewable resource such as petroleum, natural gas, or water. Mining of stones and metal has been a human activity since pre-historic times. Modern mining processes involve prospecting for ore bodies, analysis of the profit potential of a proposed mine, extraction of the desired materials, final reclamation of the land after the mine is closed. De Re Metallica, Georgius Agricola, 1550, Book I, Para. 1Mining operations create a negative environmental impact, both during the mining activity and after the mine has closed.
Hence, most of the world's nations have passed regulations to decrease the impact. Work safety has long been a concern as well, modern practices have improved safety in mines. Levels of metals recycling are low. Unless future end-of-life recycling rates are stepped up, some rare metals may become unavailable for use in a variety of consumer products. Due to the low recycling rates, some landfills now contain higher concentrations of metal than mines themselves. Since the beginning of civilization, people have used stone and metals found close to the Earth's surface; these were used to make early weapons. Flint mines have been found in chalk areas where seams of the stone were followed underground by shafts and galleries; the mines at Grimes Graves and Krzemionki are famous, like most other flint mines, are Neolithic in origin. Other hard rocks mined or collected for axes included the greenstone of the Langdale axe industry based in the English Lake District; the oldest-known mine on archaeological record is the Ngwenya Mine in Swaziland, which radiocarbon dating shows to be about 43,000 years old.
At this site Paleolithic humans mined hematite to make the red pigment ochre. Mines of a similar age in Hungary are believed to be sites where Neanderthals may have mined flint for weapons and tools. Ancient Egyptians mined malachite at Maadi. At first, Egyptians used the bright green malachite stones for ornamentations and pottery. Between 2613 and 2494 BC, large building projects required expeditions abroad to the area of Wadi Maghareh in order to secure minerals and other resources not available in Egypt itself. Quarries for turquoise and copper were found at Wadi Hammamat, Tura and various other Nubian sites on the Sinai Peninsula and at Timna. Mining in Egypt occurred in the earliest dynasties; the gold mines of Nubia were among the largest and most extensive of any in Ancient Egypt. These mines are described by the Greek author Diodorus Siculus, who mentions fire-setting as one method used to break down the hard rock holding the gold. One of the complexes is shown in one of the earliest known maps.
The miners crushed the ore and ground it to a fine powder before washing the powder for the gold dust. Mining in Europe has a long history. Examples include the silver mines of Laurium. Although they had over 20,000 slaves working them, their technology was identical to their Bronze Age predecessors. At other mines, such as on the island of Thassos, marble was quarried by the Parians after they arrived in the 7th century BC; the marble was shipped away and was found by archaeologists to have been used in buildings including the tomb of Amphipolis. Philip II of Macedon, the father of Alexander the Great, captured the gold mines of Mount Pangeo in 357 BC to fund his military campaigns, he captured gold mines in Thrace for minting coinage producing 26 tons per year. However, it was the Romans who developed large scale mining methods the use of large volumes of water brought to the minehead by numerous aqueducts; the water was used for a variety of purposes, including removing overburden and rock debris, called hydraulic mining, as well as washing comminuted, or crushed and driving simple machinery.
The Romans used hydraulic mining methods on a large scale to prospect for the veins of ore a now-obsolete form of mining known as hushing. They built numerous aqueducts to supply water to the minehead. There, the water stored in large tanks; when a full tank was opened, the flood of water sluiced away the overburden to expose the bedrock underneath and any gold veins. The rock was worked upon by fire-setting to heat the rock, which would be quenched with a stream of water; the resulting thermal shock cracked the rock, enabling it to be removed by further streams of water from the overhead tanks. The Roman miners used similar methods to work cassiterite deposits in Cornwall and lead ore in the Pennines; the methods had been developed by the Romans in Spain in 25 AD to exploit large alluvial gold deposits, the largest site being at Las Medulas, where seven long aqueducts tapped local rivers and sluiced the deposits. Spain was one of the most important mining regions, but all regions of the Roman Empire were exploited.
In Great Britain the natives had mined minerals for millennia, but after the Roman conquest, the scale of the operations increased as the Romans needed Britannia's resources gold, silver
The Hefner lamp, or in German Hefnerkerze, is a flame lamp used in photometry that burns amyl acetate. The lamp was invented by Friedrich von Hefner-Alteneck in 1884 and he proposed its use as a standard flame for photometric purposes with a luminous intensity unit of the Hefnerkerze; the lamp was specified as having an 8 mm diameter wick. The Hefner lamp provided the German and Scandinavian standard for luminosity during the late nineteenth and early twentieth centuries; the unit of light intensity was defined as that produced by the lamp burning amyl acetate with a 40 mm flame height. The light unit was known as the Hefnereinheit. In 1897 it was adopted by the Association of German Electrical Engineers under the name Hefnerkerze. Germany moved to using the New Candle from 1 July 1942 and the candela from 1948; the HK unit is still used as a measure of the intensity of kerosene pressure lamps in Germany. 1 Hefnerkerze is about 0.920 candela. Candlepower List of obsolete units of measurement "Lichtstärke und Lichteinheit".
Archived from the original on 2008-04-19
The hectare is an SI accepted metric system unit of area equal to a square with 100-metre sides, or 10,000 m2, is used in the measurement of land. There are 100 hectares in one square kilometre. An acre is about 0.405 hectare and one hectare contains about 2.47 acres. In 1795, when the metric system was introduced, the "are" was defined as 100 square metres and the hectare was thus 100 "ares" or 1⁄100 km2; when the metric system was further rationalised in 1960, resulting in the International System of Units, the are was not included as a recognised unit. The hectare, remains as a non-SI unit accepted for use with the SI units, mentioned in Section 4.1 of the SI Brochure as a unit whose use is "expected to continue indefinitely". The name was coined from the Latin ārea; the metric system of measurement was first given a legal basis in 1795 by the French Revolutionary government. The law of 18 Germinal, Year III defined five units of measure: The metre for length The are for area The stère for volume of stacked firewood The litre for volumes of liquid The gram for massIn 1960, when the metric system was updated as the International System of Units, the are did not receive international recognition.
The International Committee for Weights and Measures makes no mention of the are in the current definition of the SI, but classifies the hectare as a "Non-SI unit accepted for use with the International System of Units". In 1972, the European Economic Community passed directive 71/354/EEC, which catalogued the units of measure that might be used within the Community; the units that were catalogued replicated the recommendations of the CGPM, supplemented by a few other units including the are whose use was limited to the measurement of land. The names centiare, deciare and hectare are derived by adding the standard metric prefixes to the original base unit of area, the are; the centiare is one square metre. The deciare is ten square metres; the are is a unit of area, used for measuring land area. It was defined by older forms of the metric system, but is now outside the modern International System of Units, it is still used in colloquial speech to measure real estate, in particular in Indonesia, in various European countries.
In Russian and other languages of the former Soviet Union, the are is called sotka. It is used to describe the size of suburban dacha or allotment garden plots or small city parks where the hectare would be too large; the decare is derived from deca and are, is equal to 10 ares or 1000 square metres. It is used in Norway and in the former Ottoman areas of the Middle East and the Balkans as a measure of land area. Instead of the name "decare", the names of traditional land measures are used, redefined as one decare: Stremma in Greece Dunam, donum, or dönüm in Israel, Jordan, Lebanon and Turkey Mål is sometimes used for decare in Norway, from the old measure of about the same area; the hectare, although not a unit of SI, is the only named unit of area, accepted for use within the SI. In practice the hectare is derived from the SI, being equivalent to a square hectometre, it is used throughout the world for the measurement of large areas of land, it is the legal unit of measure in domains concerned with land ownership and management, including law, agriculture and town planning throughout the European Union.
The United Kingdom, United States, to some extent Canada use the acre instead. Some countries that underwent a general conversion from traditional measurements to metric measurements required a resurvey when units of measure in legal descriptions relating to land were converted to metric units. Others, such as South Africa, published conversion factors which were to be used "when preparing consolidation diagrams by compilation". In many countries, metrication clarified existing measures in terms of metric units; the following legacy units of area have been redefined as being equal to one hectare: Jerib in Iran Djerib in Turkey Gong Qing in Hong Kong / mainland China Manzana in Argentina Bunder in The Netherlands The most used units are in bold. One hectare is equivalent to: 1 square hectometre 15 mǔ or 0.15 qǐng 10 dunam or dönüm 10 stremmata 6.25 rai ≈ 1.008 chō ≈ 2.381 feddan Conversion of units Hecto- Hectometre Order of magnitude Official SI website: Table 6. Non-SI units accepted for use with the International System of Units
The pyramid inch is a unit of measure claimed by pyramidologists to have been used in ancient times. It was one twenty-fifth of a "sacred cubit", 1.00106 imperial inches, or 2.5426924 centimetres. The first suggestion that the builders of the Great Pyramid of Giza used units of measure related to modern measures is attributed to Oxford astronomy professor John Greaves, who journeyed to Egypt in 1638 to make measurements of the pyramid, his findings were published under his name in an anonymous tract. More than a century Greaves' measurements and additional measurements made by French engineers during Napoleon's expedition in Egypt, were studied by John Taylor. Taylor claimed that the measurements indicated that the ancients had used a unit of measure about 1/1000 greater than a modern British inch; this was the origin of the "pyramid inch". Taylor regarded the "pyramid inch" to be 1/25 of the "sacred cubit", ancient unit based on the forearm length from the tip of the middle finger to the bottom of the elbow, whose existence had earlier been postulated by Isaac Newton.
The principal argument was that the total length of the four sides of the pyramid would be 36524 if measured in pyramid inches. Taylor and his followers, who included the Astronomer Royal of Scotland Charles Piazzi Smyth found numerous apparent coincidences between the measurements of the pyramids and the geometry of the earth and the solar system, they concluded that the British system of measures was derived from a far more ancient, if not divine, system. During the 19th and early 20th centuries, this theory played a significant role in the debates over whether Britain and the United States should adopt the metric system; the theory of Taylor and Smyth gained many eminent supporters and detractors during the following decades, but by the end of the 19th century it had lost most of its mainstream scientific support. The greatest blow to the theory was dealt by the Egyptogist Flinders Petrie, whose father was a believer; when Petrie went to Egypt in 1880 to perform new measurements, he found that the pyramid was several feet smaller than believed, including the missing capstone.
This so undermined the theory that Petrie rejected it, writing "there is no authentic example, that will bear examination, of the use or existence of any such measure as a ‘Pyramid inch,’ or of a cubit of 25.025 British inches."The value of 1.00106 British inches is calculated as 1/500,000,000 of the Earth's polar diameter. The pyramid inch now appears to have no significant scientific support. No direct evidence for it has been found, so pyramidologists argue from an increasing list of alleged numerical coincidences