1.
Operation Plumbbob
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Operation Plumbbob was a series of nuclear tests conducted between May 28 and October 7,1957, at the Nevada Test Site, following Project 57, and preceding Project 58/58A. It was the biggest, longest, and most controversial test series in the continental United States, the operation consisted of 29 explosions, of which only two did not produce any nuclear yield. Twenty-one laboratories and government agencies were involved and they included forty-three military effects tests on civil and military structures, radiation and bio-medical studies, and aircraft structural tests. Operation Plumbbob had the tallest tower tests to date in the U. S. nuclear testing program as well as high-altitude balloon tests, one nuclear test involved the largest troop maneuver ever associated with U. S. nuclear testing. Approximately 18,000 members of the U. S. Air Force, Army, Navy, the military was interested in knowing how the average foot-soldier would stand up, physically and psychologically, to the rigors of the tactical nuclear battlefield. Almost 1,200 pigs were subjected to experiments and blast-effects studies during Operation Plumbbob. On shot Priscilla,719 pigs were used in experiments on Frenchman Flat. Some pigs were placed in elevated cages and provided with suits made of different materials, as shown and reported in the PBS documentary Dark Circle, the pigs survived, but with third-degree burns to 80% of their bodies. Other pigs were placed in pens behind large sheets of glass at measured distances from the hypocenter to test the effects of flying debris on living targets, nuclear weapons safety experiments were conducted to study the possibility of a nuclear weapon detonation during an accident. On July 26,1957, a safety experiment, Pascal-A, was detonated in a hole at NTS. The knowledge gained here would provide data to prevent nuclear yields in case of accidental detonations–for example, the John shot on July 19,1957 was the only test of the Air Forces AIR-2 Genie missile with a nuclear warhead. It was fired from an F-89 Scorpion fighter over Yucca Flats at the NNSS, in 2012 the photographer and the last survivor of the five met in a restaurant in Dallas to reminisce. The five officers were, Colonel Sidney C, bruce, later professor of Electrical Engineering at Colorado University, died in 2005, Lieutenant Colonel Frank P. Ball, died in 2003, Major John w. Hughes II, died in 1990, Major Norman B. Bodinger, died February 2,1997, Major Donald A. Luttrell, the photographer, Akira George Yoshitake, died in October 2013. The Rainier shot, conducted September 19,1957, was the first fully contained underground nuclear test and this test of 1.7 kt could be detected around the world by seismologists using ordinary seismic instruments. The Rainier test became the prototype for larger and more powerful underground tests, some images from Upshot-Knothole Grable were accidentally relabeled as belonging to the Priscilla shot from Operation Plumbbob in 1957. As a consequence many publications including official government documents have the photo mislabeled, Plumbbob released 58,300 kilocuries of radioiodine into the atmosphere. This produced total civilian radiation exposures amounting to 120 million person-rads of thyroid tissue exposure
2.
Spirit level
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A spirit level, bubble level or simply a level is an instrument designed to indicate whether a surface is horizontal or vertical. Early spirit levels had very slightly curved glass vials with constant inner diameter at each viewing point and these vials are incompletely filled with a liquid, usually a colored spirit or alcohol, leaving a bubble in the tube. They have an upward curve, so that the bubble naturally rests in the center. At slight inclinations the bubble travels away from the center position. Where a spirit level must also be usable upside-down or on its side, alcohols such as ethanol are often used rather than water. Alcohols have low viscosity and surface tension, which allows the bubble to travel the tube quickly, alcohols also have a much wider liquid temperature range, and wont break the vial as water could due to ice expansion. A colorant such as fluorescein, typically yellow or green, may be added to increase the visibility of the bubble. An extension of the level is the bulls eye level. It serves to level a surface across a plane, while the level only does so in the direction of the tube. To check the accuracy of a carpenters type level, a horizontal surface is not needed. The level is placed on a flat and roughly level surface and this reading indicates to what extent the surface is parallel to the horizontal plane, according to the level, which at this stage is of unknown accuracy. The spirit level is then rotated through 180 degrees in the horizontal plane, if the level is accurate, it will indicate the same orientation with respect to the horizontal plane. A difference implies that the level is inaccurate, a similar procedure is applied to more sophisticated instruments such as a surveyors level or a theodolite and is a matter of course each time the instrument is set up. In this latter case, the plane of rotation of the instrument is levelled and this is done in two horizontal perpendicular directions. The sensitivity is an important specification for a level, its accuracy depends on its sensitivity. The sensitivity of a level is given as the change of angle or gradient required to move the bubble by unit distance, if the bubble housing has graduated divisions then the sensitivity is the angle or gradient change that moves the bubble by one of these divisions. 2 mm is the spacing for graduations, on a surveyors level the bubble will move 2 mm when the vial is tilted about 0.005 degree. For a precision machinist level with 2mm divisions, when the vial is tilted 5 arc seconds the bubble will move one graduation and this is equivalent to movement of.0005 inches measured one foot from the pivot point, referred to as 5 ten-thousandths per foot
3.
Measuring instrument
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A measuring instrument is a device for measuring a physical quantity. In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item under study, measuring instruments, and formal test methods which define the instruments use, are the means by which these relations of numbers are obtained. All measuring instruments are subject to varying degrees of instrument error, scientists, engineers and other humans use a vast range of instruments to perform their measurements. These instruments may range from simple objects such as rulers and stopwatches to electron microscopes, virtual instrumentation is widely used in the development of modern measuring instruments. In the past, a common time measuring instrument was the sundial, today, the usual measuring instruments for time are clocks and watches. For highly accurate measurement of time a clock is used. Stop watches are used to measure time in some sports. Energy is measured by an energy meter, examples of energy meters include, An electricity meter measures energy directly in kilowatt hours. A gas meter measures energy indirectly by recording the volume of gas used and this figure can then be converted to a measure of energy by multiplying it by the calorific value of the gas. A physical system that exchanges energy may be described by the amount of energy exchanged per time-interval, for the ranges of power-values see, Orders of magnitude. Action describes energy summed up over the time a process lasts and its dimension is the same as that of an angular momentum. A phototube provides a measurement which permits the calculation of the quantized action of light. This includes basic quantities found in classical- and continuum mechanics, dumpy level Laser line level Spirit level Gyroscope Ballistic pendulum, indirectly by calculation and or gauging Considerations related to electric charge dominate electricity and electronics. Electrical charges interact via a field and that field is called electric if the charge doesnt move. If the charge moves, thus realizing an electric current, especially in a neutral conductor. Electricity can be given a quality — a potential, and electricity has a substance-like property, the electric charge. Energy in elementary electrodynamics is calculated by multiplying the potential by the amount of charge found at that potential, potential times charge, electrometer is often used to reconfirm the phenomenon of contact electricity leading to triboelectric sequences
4.
Ancient Egypt
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Ancient Egypt was a civilization of ancient Northeastern Africa, concentrated along the lower reaches of the Nile River in what is now the modern country of Egypt. It is one of six civilizations to arise independently, Egyptian civilization followed prehistoric Egypt and coalesced around 3150 BC with the political unification of Upper and Lower Egypt under the first pharaoh Narmer. In the aftermath of Alexander the Greats death, one of his generals, Ptolemy Soter and this Greek Ptolemaic Kingdom ruled Egypt until 30 BC, when, under Cleopatra, it fell to the Roman Empire and became a Roman province. The success of ancient Egyptian civilization came partly from its ability to adapt to the conditions of the Nile River valley for agriculture, the predictable flooding and controlled irrigation of the fertile valley produced surplus crops, which supported a more dense population, and social development and culture. Its art and architecture were widely copied, and its antiquities carried off to far corners of the world and its monumental ruins have inspired the imaginations of travelers and writers for centuries. The Nile has been the lifeline of its region for much of human history, nomadic modern human hunter-gatherers began living in the Nile valley through the end of the Middle Pleistocene some 120,000 years ago. By the late Paleolithic period, the climate of Northern Africa became increasingly hot and dry. In Predynastic and Early Dynastic times, the Egyptian climate was less arid than it is today. Large regions of Egypt were covered in treed savanna and traversed by herds of grazing ungulates, foliage and fauna were far more prolific in all environs and the Nile region supported large populations of waterfowl. Hunting would have been common for Egyptians, and this is also the period when many animals were first domesticated. The largest of these cultures in upper Egypt was the Badari, which probably originated in the Western Desert, it was known for its high quality ceramics, stone tools. The Badari was followed by the Amratian and Gerzeh cultures, which brought a number of technological improvements, as early as the Naqada I Period, predynastic Egyptians imported obsidian from Ethiopia, used to shape blades and other objects from flakes. In Naqada II times, early evidence exists of contact with the Near East, particularly Canaan, establishing a power center at Hierakonpolis, and later at Abydos, Naqada III leaders expanded their control of Egypt northwards along the Nile. They also traded with Nubia to the south, the oases of the desert to the west. Royal Nubian burials at Qustul produced artifacts bearing the oldest-known examples of Egyptian dynastic symbols, such as the crown of Egypt. They also developed a ceramic glaze known as faience, which was used well into the Roman Period to decorate cups, amulets, and figurines. During the last predynastic phase, the Naqada culture began using written symbols that eventually were developed into a system of hieroglyphs for writing the ancient Egyptian language. The Early Dynastic Period was approximately contemporary to the early Sumerian-Akkadian civilisation of Mesopotamia, the third-century BC Egyptian priest Manetho grouped the long line of pharaohs from Menes to his own time into 30 dynasties, a system still used today
5.
Surveying
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Surveying or land surveying is the technique, profession, and science of determining the terrestrial or three-dimensional position of points and the distances and angles between them. A land surveying professional is called a land surveyor, Surveyors work with elements of geometry, trigonometry, regression analysis, physics, engineering, metrology, programming languages and the law. Surveying has been an element in the development of the environment since the beginning of recorded history. The planning and execution of most forms of construction require it and it is also used in transport, communications, mapping, and the definition of legal boundaries for land ownership. It is an important tool for research in other scientific disciplines. Basic surveyance has occurred since humans built the first large structures, the prehistoric monument at Stonehenge was set out by prehistoric surveyors using peg and rope geometry. In ancient Egypt, a rope stretcher would use simple geometry to re-establish boundaries after the floods of the Nile River. The almost perfect squareness and north-south orientation of the Great Pyramid of Giza, built c.2700 BC, the Groma instrument originated in Mesopotamia. The mathematician Liu Hui described ways of measuring distant objects in his work Haidao Suanjing or The Sea Island Mathematical Manual, the Romans recognized land surveyors as a profession. They established the basic measurements under which the Roman Empire was divided, Roman surveyors were known as Gromatici. In medieval Europe, beating the bounds maintained the boundaries of a village or parish and this was the practice of gathering a group of residents and walking around the parish or village to establish a communal memory of the boundaries. Young boys were included to ensure the memory lasted as long as possible, in England, William the Conqueror commissioned the Domesday Book in 1086. It recorded the names of all the owners, the area of land they owned, the quality of the land. It did not include maps showing exact locations, abel Foullon described a plane table in 1551, but it is thought that the instrument was in use earlier as his description is of a developed instrument. Gunters chain was introduced in 1620 by English mathematician Edmund Gunter and it enabled plots of land to be accurately surveyed and plotted for legal and commercial purposes. Leonard Digges described a Theodolite that measured horizontal angles in his book A geometric practice named Pantometria, joshua Habermel created a theodolite with a compass and tripod in 1576. Johnathon Sission was the first to incorporate a telescope on a theodolite in 1725, in the 18th century, modern techniques and instruments for surveying began to be used. Jesse Ramsden introduced the first precision theodolite in 1787 and it was an instrument for measuring angles in the horizontal and vertical planes
6.
Nadir
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The nadir, is the direction pointing directly below a particular location, that is, it is one of two vertical directions at a specified location, orthogonal to a horizontal flat surface there. Since the concept of being below is itself somewhat vague, scientists define the nadir in more rigorous terms. Specifically, in astronomy, geophysics and related sciences, the nadir at a point is the local vertical direction pointing in the direction of the force of gravity at that location. The direction opposite of the nadir is the zenith, the word is also used figuratively to mean the lowest point of a persons spirits, or the quality of an activity or profession. The term nadir can also be used to represent the lowest point reached by a body during its apparent orbit around a given point of observation. This can be used to describe the location of the Sun, the sun is said to be at the nadir at a location when it is at the zenith at the locations antipode and the sun is 90 degrees below the horizon. In oncology, the nadir is used to represent the lowest level of a blood cell count while a patient is undergoing chemotherapy. A diagnosis of neutropenic nadir after chemotherapy typically lasts 7–10 days
7.
Theodolite
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A theodolite /θiːˈɒdəlaɪt/ is a precision instrument for measuring angles in the horizontal and vertical planes. Theodolites are used mainly for surveying applications, and have adapted for specialized purposes such as meteorology. A modern theodolite consists of a telescope mounted within two perpendicular axes, the horizontal or trunnion axis and the zenith axis. A theodolite measures vertical angles as angles between the zenith, forwards or plunged—typically approximately 90 and 270 degrees, when the telescope is pointed at a target object, the angle of each of these axes can be measured with great precision, typically to seconds of arc. A theodolite may be either transit or non-transit, in a transit theodolite, the telescope can be inverted in the vertical plane, whereas the rotation in the same plane is restricted to a semi-circle in a non-transit theodolite. Some types of transit theodolites do not allow the measurement of vertical angles, the builders level is sometimes mistaken for a transit theodolite, but it measures neither horizontal nor vertical angles. It uses a level to set a telescope level to define a line of sight along a horizontal plane. A theodolite is mounted on its head by means of a forced centering plate or tribrach containing four thumbscrews, or in modern theodolites. Before use, a theodolite must be placed vertically above the point to be measured using a plumb bob. The instrument is then set level using leveling footscrews and circular, both axes of a theodolite are equipped with graduated circles that can be read through magnifying lenses. The vertical circle which transits about the horizontal axis should read 90° when the axis is horizontal, or 270° when the instrument is in its second position. Half of the difference between the two positions is called the index error, the horizontal and vertical axes of a theodolite must be perpendicular, if not then a horizontal axis error exists. This can be tested by aligning the tubular spirit bubble parallel to a line between two footscrews and setting the bubble central, a horizontal axis error is present if the bubble runs off central when the tubular spirit bubble is reversed. To adjust, the operator removes 1/2 the amount the bubble has run off using the screw, then re-level, test. If not, then a collimation error exists, index error, horizontal axis error and collimation error are regularly determined by calibration and are removed by mechanical adjustment. Their existence is taken account in the choice of measurement procedure in order to eliminate their effect on the measurement results of the theodolite. The term diopter was used in old texts as a synonym for theodolite. This derives from an astronomical instrument called a dioptra
8.
Tape measure
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A tape measure or measuring tape is a flexible ruler. It consists of a ribbon of cloth, plastic, fibre glass and it is a common measuring tool. Its design allows for a measure of length to be easily carried in pocket or toolkit. Today it is ubiquitous, even appearing in miniature form as a keychain fob, Surveyors use tape measures in lengths of over 100 m. Tape measures that were intended for use in tailoring or dressmaking were made from cloth or plastic. These types of tape measures were mainly used for the measuring of the humans waist line. Today, measuring tapes made for sewing are made of fiberglass, measuring tapes designed for carpentry or construction often use a stiff, curved metallic ribbon that can remain stiff and straight when extended, but retracts into a coil for convenient storage. This type of measure will have a floating tang or hook on the end to aid measuring. The tang is connected to the tape with loose rivets through oval holes, a tape measure of 25 or even 100 feet can wind into a relatively small container. The self-marking tape measure allows the user an accurate one hand measure, the first record of a people using a measuring device was by the Romans using marked strips of leather, but this was more like a regular ruler than a tape measure. On July 14,1868, a patent was filed by one Alvin J. Fellows of New Haven, Fellows rule, although crude and flimsy, was the first attempt to make a spring tape measure. On 3 January 1922, Hiram A. Farrand received the patent he filed in 1919 for his tape measure. Sometime between 1922 and December 1926, Farrand experimented with the help of The Brown Company in Berlin and it is there Hiram and William Wentworth Brown began mass-producing the tape measure. Their product was sold to Stanley Works. The basic design on all modern spring tape measures are built can trace its origins back to an 1868 patent by a New Haven. According to the text of his patent, Fellows tape measure was an improvement on other versions previously designed, the spring tape measure has existed since Fellows patent in 1868, but its usage did not become very popular due to the difficulty in communication from one town to another. In the early 1900s, carpenters began slowly adopting H. A. Farrands design as the one commonly used. With the mass production of the circuit the tape measure has also entered into the digital age with the digital tape measure. Some incorporate a digital screen to give measurement readouts in multiple formats, an early patent for this type of measure was published in 1977
9.
Survey marker
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Survey markers, also called survey marks, survey monuments, or geodetic marks, are objects placed to mark key survey points on the Earths surface. They are used in geodetic and land surveying, informally, such marks are referred to as benchmarks, although strictly speaking the term benchmark is reserved for marks that indicate elevation. Horizontal position markers used for triangulation are also known as triangulation stations, all sorts of different objects, ranging from the familiar brass disks to liquor bottles, clay pots, and rock cairns, have been used over the years as survey markers. Some truly monumental markers have used to designate tripoints, or the meeting points of three or more countries. In the 19th century, these marks were often drill holes in rock ledges, crosses or triangles chiselled in rock and these marks are intended to be permanent, and disturbing them is generally prohibited by federal and state law. Such surveys laid the basis for map-making in the United States, Geodetic survey markers were often set in groups. For example, in surveys, the primary point identified was called the triangulation station. A triangulation station was surrounded by several reference marks, each of which bore an arrow that pointed back towards the main station. These reference marks made it easier for visitors to recover the primary mark. Reference marks also made it possible to replace a station mark that had been disturbed or destroyed, some old station marks were buried several feet down. Occasionally, these buried marks had surface marks set directly above them, in the U. S. survey marks that meet certain standards for accuracy are part of a national database that is maintained by the National Geodetic Survey. Each station mark in the database has a PID, a unique 6-character code that can be used to call up a datasheet describing that station, the NGS has a web-based form that can be used to access any datasheet, if the stations PID is known. Alternatively, datasheets can be called up by station name, a typical datasheet has either the precise or the estimated coordinates. Precise coordinates are called adjusted and result from precise surveys, estimated coordinates are termed scaled and have usually been set by locating the point on a map and reading off its latitude and longitude. Scaled coordinates can be as much as several feet distant from the true positions of their marks. Survey markers are now used to set up a GPS receiver antenna in a known position for use in Differential GPS surveying. Boundary marker Milestone No website will allow for searching of USGS Marks and this website provides a state-by-state mapping of NGS survey marks on to Google Maps, enabling one to search for these marks visually. Links to the listings on Geocaching. com are also provided
10.
Lead
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Lead is a chemical element with atomic number 82 and symbol Pb. When freshly cut, it is bluish-white, it tarnishes to a dull gray upon exposure to air and it is a soft, malleable, and heavy metal with a density exceeding that of most common materials. Lead has the second-highest atomic number of the stable elements. Lead is a relatively unreactive post-transition metal and its weak metallic character is illustrated by its amphoteric nature and tendency to form covalent bonds. Compounds of lead are found in the +2 oxidation state. Exceptions are mostly limited to organolead compounds, like the lighter members of the group, lead exhibits a tendency to bond to itself, it can form chains, rings, and polyhedral structures. Lead is easily extracted from its ores and was known to people in Western Asia. A principal ore of lead, galena, often bears silver, Lead production declined after the fall of Rome and did not reach comparable levels again until the Industrial Revolution. Nowadays, global production of lead is about ten million tonnes annually, Lead has several properties that make it useful, high density, low melting point, ductility, and relative inertness to oxidation. In the late 19th century, lead was recognized as poisonous, Lead is a neurotoxin that accumulates in soft tissues and bones, damaging the nervous system and causing brain disorders and, in mammals, blood disorders. A lead atom has 82 electrons, arranged in a configuration of 4f145d106s26p2. The combined first and second ionization energies—the total energy required to remove the two 6p electrons—is close to that of tin, leads upper neighbor in group 14. This is unusual since ionization energies generally fall going down a group as an elements outer electrons become more distant from the nucleus, the similarity is caused by the lanthanide contraction—the decrease in element radii from lanthanum to lutetium, and the relatively small radii of the elements after hafnium. The contraction is due to shielding of the nucleus by the lanthanide 4f electrons. The combined first four ionization energies of lead exceed those of tin, for this reason lead, unlike tin, mostly forms compounds in which it has an oxidation state of +2, rather than +4. Relativistic effects, which become particularly prominent at the bottom of the periodic table, as a result, the 6s electrons of lead become reluctant to participate in bonding, a phenomenon called the inert pair effect. A related outcome is that the distance between nearest atoms in crystalline lead is unusually long, the lighter group 14 elements form stable or metastable allotropes having the tetrahedrally coordinated and covalently bonded diamond cubic structure. The energy levels of their outer s- and p-orbitals are close enough to allow mixing into four hybrid sp3 orbitals
11.
Latin
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Latin is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets, Latin was originally spoken in Latium, in the Italian Peninsula. Through the power of the Roman Republic, it became the dominant language, Vulgar Latin developed into the Romance languages, such as Italian, Portuguese, Spanish, French, and Romanian. Latin, Italian and French have contributed many words to the English language, Latin and Ancient Greek roots are used in theology, biology, and medicine. By the late Roman Republic, Old Latin had been standardised into Classical Latin, Vulgar Latin was the colloquial form spoken during the same time and attested in inscriptions and the works of comic playwrights like Plautus and Terence. Late Latin is the language from the 3rd century. Later, Early Modern Latin and Modern Latin evolved, Latin was used as the language of international communication, scholarship, and science until well into the 18th century, when it began to be supplanted by vernaculars. Ecclesiastical Latin remains the language of the Holy See and the Roman Rite of the Catholic Church. Today, many students, scholars and members of the Catholic clergy speak Latin fluently and it is taught in primary, secondary and postsecondary educational institutions around the world. The language has been passed down through various forms, some inscriptions have been published in an internationally agreed, monumental, multivolume series, the Corpus Inscriptionum Latinarum. Authors and publishers vary, but the format is about the same, volumes detailing inscriptions with a critical apparatus stating the provenance, the reading and interpretation of these inscriptions is the subject matter of the field of epigraphy. The works of several hundred ancient authors who wrote in Latin have survived in whole or in part and they are in part the subject matter of the field of classics. The Cat in the Hat, and a book of fairy tales, additional resources include phrasebooks and resources for rendering everyday phrases and concepts into Latin, such as Meissners Latin Phrasebook. The Latin influence in English has been significant at all stages of its insular development. From the 16th to the 18th centuries, English writers cobbled together huge numbers of new words from Latin and Greek words, dubbed inkhorn terms, as if they had spilled from a pot of ink. Many of these words were used once by the author and then forgotten, many of the most common polysyllabic English words are of Latin origin through the medium of Old French. Romance words make respectively 59%, 20% and 14% of English, German and those figures can rise dramatically when only non-compound and non-derived words are included. Accordingly, Romance words make roughly 35% of the vocabulary of Dutch, Roman engineering had the same effect on scientific terminology as a whole
12.
French language
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French is a Romance language of the Indo-European family. It descended from the Vulgar Latin of the Roman Empire, as did all Romance languages, French has evolved from Gallo-Romance, the spoken Latin in Gaul, and more specifically in Northern Gaul. Its closest relatives are the other langues doïl—languages historically spoken in northern France and in southern Belgium, French was also influenced by native Celtic languages of Northern Roman Gaul like Gallia Belgica and by the Frankish language of the post-Roman Frankish invaders. Today, owing to Frances past overseas expansion, there are numerous French-based creole languages, a French-speaking person or nation may be referred to as Francophone in both English and French. French is a language in 29 countries, most of which are members of la francophonie. As of 2015, 40% of the population is in Europe, 35% in sub-Saharan Africa, 15% in North Africa and the Middle East, 8% in the Americas. French is the fourth-most widely spoken mother tongue in the European Union, 1/5 of Europeans who do not have French as a mother tongue speak French as a second language. As a result of French and Belgian colonialism from the 17th and 18th century onward, French was introduced to new territories in the Americas, Africa, most second-language speakers reside in Francophone Africa, in particular Gabon, Algeria, Mauritius, Senegal and Ivory Coast. In 2015, French was estimated to have 77 to 110 million native speakers, approximately 274 million people are able to speak the language. The Organisation internationale de la Francophonie estimates 700 million by 2050, in 2011, Bloomberg Businessweek ranked French the third most useful language for business, after English and Standard Mandarin Chinese. Under the Constitution of France, French has been the language of the Republic since 1992. France mandates the use of French in official government publications, public education except in specific cases, French is one of the four official languages of Switzerland and is spoken in the western part of Switzerland called Romandie, of which Geneva is the largest city. French is the language of about 23% of the Swiss population. French is also a language of Luxembourg, Monaco, and Aosta Valley, while French dialects remain spoken by minorities on the Channel Islands. A plurality of the worlds French-speaking population lives in Africa and this number does not include the people living in non-Francophone African countries who have learned French as a foreign language. Due to the rise of French in Africa, the total French-speaking population worldwide is expected to reach 700 million people in 2050, French is the fastest growing language on the continent. French is mostly a language in Africa, but it has become a first language in some urban areas, such as the region of Abidjan, Ivory Coast and in Libreville. There is not a single African French, but multiple forms that diverged through contact with various indigenous African languages, sub-Saharan Africa is the region where the French language is most likely to expand, because of the expansion of education and rapid population growth
13.
Dome
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A dome is an architectural element that resembles the hollow upper half of a sphere. The precise definition has been a matter of controversy, there are also a wide variety of forms and specialized terms to describe them. A dome can rest upon a rotunda or drum, and can be supported by columns or piers that transition to the dome through squinches or pendentives, a lantern may cover an oculus and may itself have another dome. Domes have a long architectural lineage that extends back into prehistory and they have been constructed from mud, snow, stone, wood, brick, concrete, metal, glass, and plastic over the centuries. The symbolism associated with domes includes mortuary, celestial, and governmental traditions that have developed over time. Domes have been found from early Mesopotamia, which may explain the forms spread and they are found in Persian, Hellenistic, Roman, and Chinese architecture in the Ancient world, as well as among a number of contemporary indigenous building traditions. They were popular in Byzantine and medieval Islamic architecture, and there are examples from Western Europe in the Middle Ages. The Renaissance style spread from Italy in the Early modern period, advancements in mathematics, materials, and production techniques since that time resulted in new dome types. The domes of the world can be found over religious buildings, legislative chambers, sports stadiums. The English word dome ultimately derives from the Latin domus —which, up through the Renaissance, labeled a revered house, such as a Domus Dei, or House of God, the French word dosme came to acquire the meaning of a cupola vault, specifically, by 1660. A dome is a rounded vault made of either curved segments or a shell of revolution, sometimes called false domes, corbel domes achieve their shape by extending each horizontal layer of stones inward slightly farther than the lower one until they meet at the top. A false dome may also refer to a wooden dome, true domes are said to be those whose structure is in a state of compression, with constituent elements of wedge-shaped voussoirs, the joints of which align with a central point. The validity of this is unclear, as domes built underground with corbelled stone layers are also in compression from the surrounding earth, as with arches, the springing of a dome is the level from which the dome rises. The top of a dome is the crown, the inner side of a dome is called the intrados and the outer side is called the extrados. The haunch is the part of an arch that lies halfway between the base and the top. The word cupola is another word for dome, and is used for a small dome upon a roof or turret. Cupola has also used to describe the inner side of a dome. Drums, also called tholobates, are cylindrical or polygonal walls with or without windows that support a dome, a tambour or lantern is the equivalent structure over a domes oculus, supporting a cupola
14.
Tower
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A tower is a tall structure, taller than it is wide, often by a significant margin. Towers are distinguished from masts by their lack of guy-wires and are therefore, along with tall buildings, Towers are specifically distinguished from buildings in that they are not built to be habitable but to serve other functions. Towers can be stand alone structures or be supported by adjacent buildings or can be a feature on top of a structure or building. Old English torr is from Latin turris via Old French tor, the Latin term together with Greek τύρσις was loaned from a pre-Indo-European Mediterranean language, connected with the Illyrian toponym Βου-δοργίς. The oldest known may be the stone tower in walls of Neolithic Jericho. Some of the earliest towers were ziggurats, which existed in Sumerian architecture since the 4th millennium BC, the most famous ziggurats include the Sumerian Ziggurat of Ur, built the 3rd millennium BC, and the Etemenanki, one of the most famous examples of Babylonian architecture. The latter was built in Babylon during the 2nd millennium BC and was considered the tallest tower of the ancient world, some of the earliest surviving examples are the broch structures in northern Scotland, which are conical towerhouses. These and other examples from Phoenician and Roman cultures emphasised the use of a tower in fortification, for example, the name of the Moroccan city of Mogador, founded in the first millennium BC, is derived from the Phoenician word for watchtower. The Romans utilised octagonal towers as elements of Diocletians Palace in Croatia, which monument dates to approximately 300 AD, while the Servian Walls, the Chinese used towers as integrated elements of the Great Wall of China in 210 BC during the Qin Dynasty. Towers were also an important element of castles, other well known towers include the Leaning Tower of Pisa in Pisa, Italy built from 1173 until 1372 and the Two Towers in Bologna, Italy built from 1109 until 1119. The Himalayan Towers are stone towers located chiefly in Tibet built approximately 14th to 15th century, up to a certain height, a tower can be made with the supporting structure with parallel sides. However, above a height, the compressive load of the material is exceeded. This can be avoided if the support structure tapers up the building. A second limit is that of buckling—the structure requires sufficient stiffness to avoid breaking under the loads it faces, many very tall towers have their support structures at the periphery of the building, which greatly increases the overall stiffness. A third limit is dynamic, a tower is subject to varying winds, vortex shedding and these are often dealt with through a combination of simple strength and stiffness, as well as in some cases tuned mass dampers to damp out movements. Varying or tapering the outer aspect of the tower with height avoids vibrations due to vortex shedding occurring along the building simultaneously. Although not correctly called towers many modern skyscraper are often called towers, in the United Kingdom, tall domestic buildings are referred to as tower blocks. In the United States, the original World Trade Center had the nickname the Twin Towers, the tower throughout history has provided its users with an advantage in surveying defensive positions and obtaining a better view of the surrounding areas, including battlefields
15.
Inclinometer
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A clinometer or inclinometer is an instrument for measuring angles of slope, elevation or depression of an object with respect to gravity. It is also known as a meter, tilt indicator, slope alert, slope gauge, gradient meter, gradiometer, level gauge, level meter, declinometer. Clinometers measure both inclines and declines using three different units of measure, degrees, percent, and topo, astrolabes are inclinometers that were used for navigation and locating astronomical objects from ancient times to the Renaissance. In aircraft, the ball in turn coordinators or turn and bank indicators is sometimes referred to as an inclinometer. Inclinometers include examples such as Wells in-clinometer, the parts of which are a flat side, or base, on which it stands. The glass face of the disk is surrounded by a scale that marks the angle at which the surface of the liquid stands. A forester using a clinometer makes use of basic trigonometry, first the observer measures a straight-line distance D from some observation point O to the object. Then, using the clinometer, the measures the angle a between O and the top of the object. Then the observer does the same for the angle b between O and the bottom of the object, multiplying D by the tangent of a gives the height of the object above the observer, and by the tangent of b the depth of the object below the observer. Adding the two of course gives the height of the object. The forester stands at a distance from the base of the tree. The most common distances in the United States are 50 feet and 66 feet, to obtain accurate readings it is best to use taped measured distance instead of paced distances. For the most accurate readings it is best to use a distance that is not less than the height of the tree being measured, that is, the observer sights to the top of tree, if total height is the desired measurement. If the desired measurement is merchantable height—that is, the height producing timber that can be sold—the observer sights to a point on the tree above which no more merchantable timber is found, note that the observer should use slopes expressed as a percent. The observer then measures to the bottom of the tree, again using percents, the observer than takes the slope to the top of the tree, and subtracts the slope of the bottom of the tree from it. Note that when the ground slopes downwards, the observer will record a negative slope to the base of the tree, when this is subtracted from the slope to the top of the tree, it is actually being added. These numbers are divided by 100, and multiplied by the distance from the tree. There is still some error in this number, because the distance is measured along the ground, by standing at the base of the tree, the observer should mark his/her eye level
16.
Shock absorber
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A shock absorber is a mechanical or hydraulic device designed to absorb and damp shock impulses. It does this by converting the energy of the shock into another form of energy which is then dissipated. Most shock absorbers are a form of dashpot, pneumatic and hydraulic shock absorbers are used in conjunction with cushions and springs. An automobile shock absorber contains spring-loaded check valves and orifices to control the flow of oil through an internal piston, one design consideration, when designing or choosing a shock absorber, is where that energy will go. In most shock absorbers, energy is converted to heat inside the viscous fluid, in hydraulic cylinders, the hydraulic fluid heats up, while in air cylinders, the hot air is usually exhausted to the atmosphere. In other types of shock absorbers, such as electromagnetic types, in general terms, shock absorbers help cushion vehicles on uneven roads. In a vehicle, shock absorbers reduce the effect of traveling over rough ground, leading to improved ride quality, while shock absorbers serve the purpose of limiting excessive suspension movement, their intended sole purpose is to damp spring oscillations. Shock absorbers use valving of oil and gasses to absorb energy from the springs. Spring rates are chosen by the based on the weight of the vehicle. Some people use shocks to modify spring rates but this is not the correct use, along with hysteresis in the tire itself, they damp the energy stored in the motion of the unsprung weight up and down. Effective wheel bounce damping may require tuning shocks to an optimal resistance, spring-based shock absorbers commonly use coil springs or leaf springs, though torsion bars are used in torsional shocks as well. Ideal springs alone, however, are not shock absorbers, as only store. Vehicles typically employ both hydraulic shock absorbers and springs or torsion bars, in this combination, shock absorber refers specifically to the hydraulic piston that absorbs and dissipates vibration. Now, composite suspension system are used mainly in 2 wheelers, in common with carriages and railway locomotives, most early motor vehicles used leaf springs. However the amount of damping provided by leaf spring friction was limited and variable according to the conditions of the springs and it also operated in both directions. Motorcycle front suspension adopted coil sprung Druid forks from about 1906, and similar designs later added rotary friction dampers and these friction disk shock absorbers were also fitted to many cars. One of the problems with motor cars was the variation in sprung weight between lightly loaded and fully loaded, especially for the rear springs. What was called for was damping that operated on the rebound, horock came up with a design in 1901 that had hydraulic damping, it worked in one direction only
17.
Figure drawing
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A figure drawing is a drawing of the human form in any of its various shapes and postures using any of the drawing media. The term can refer to the act of producing such a drawing. The degree of representation may range from detailed, anatomically correct renderings to loose. A life drawing is a drawing of the figure from observation of a live model. A figure drawing may be a work of art or a figure study done in preparation for a more finished work such as a painting. Figure drawing is arguably the most difficult subject an artist commonly encounters, the human figure is one of the most enduring themes in the visual arts, and the human figure can be the basis of portraiture, illustration, sculpture, medical illustration, and other fields. Artists take a variety of approaches to drawing the human figure and they may draw from live models or from photographs, from skeletal models, or from memory and imagination. Most instruction focuses on the use of models in life drawing courses, in developing the image, some artists focus on the shapes created by the interplay of light and dark values on the surfaces of the body. For those working without visual reference, proportions commonly recommended in figure drawing are and this can be illustrated to students in the classroom using paper plates to visually demonstrate the length of their bodies. An ideal figure, used for an impression of nobility or grace, is drawn at 8 heads tall, a heroic figure used in the depiction of gods and superheroes is eight-and-a-half heads tall. Most of the length comes from a bigger chest and longer legs. Note that these proportions are most useful for a standing model, poses which introduce foreshortening of various body parts will cause them to differ. The French Salon in the 19th century recommended the use of Conté crayons, erasure was not permitted, instead, the artist was expected to describe the figure in light strokes before making darker, more visible marks. A popular modern technique is the use of a stick, prepared from special vines. The charcoal adheres loosely to the paper, allowing very easy erasure, harder compressed charcoal can produce a more deliberate and precise effect, and graduated tones can be produced by smudging with the fingers or with a cylindrical paper tool called a stump. Graphite pencil is also used for figure drawing. For this purpose artists pencils are sold in formulations, ranging from 9B to 1B. Like charcoal, it can be erased and manipulated using a stump, the artist will often start with graphite pencil to sketch or outline the drawing, then the final line work is done with a pen or brush, with permanent ink
18.
Center of gravity
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The distribution of mass is balanced around the center of mass and the average of the weighted position coordinates of the distributed mass defines its coordinates. Calculations in mechanics are simplified when formulated with respect to the center of mass. It is a point where entire mass of an object may be assumed to be concentrated to visualise its motion. In other words, the center of mass is the equivalent of a given object for application of Newtons laws of motion. In the case of a rigid body, the center of mass is fixed in relation to the body. The center of mass may be located outside the body, as is sometimes the case for hollow or open-shaped objects. In the case of a distribution of separate bodies, such as the planets of the Solar System, in orbital mechanics, the equations of motion of planets are formulated as point masses located at the centers of mass. The center of mass frame is a frame in which the center of mass of a system is at rest with respect to the origin of the coordinate system. The concept of center of mass in the form of the center of gravity was first introduced by the ancient Greek physicist, mathematician, and engineer Archimedes of Syracuse. He worked with simplified assumptions about gravity that amount to a uniform field, in work on floating bodies he demonstrated that the orientation of a floating object is the one that makes its center of mass as low as possible. He developed mathematical techniques for finding the centers of mass of objects of uniform density of various well-defined shapes, Newtons second law is reformulated with respect to the center of mass in Eulers first law. The center of mass is the point at the center of a distribution of mass in space that has the property that the weighted position vectors relative to this point sum to zero. In analogy to statistics, the center of mass is the location of a distribution of mass in space. Solving this equation for R yields the formula R =1 M ∑ i =1 n m i r i, solve this equation for the coordinates R to obtain R =1 M ∭ Q ρ r d V, where M is the total mass in the volume. If a continuous mass distribution has density, which means ρ is constant. The center of mass is not generally the point at which a plane separates the distribution of mass into two equal halves, in analogy with statistics, the median is not the same as the mean. The coordinates R of the center of mass of a system, P1 and P2, with masses m1. The percentages of mass at each point can be viewed as projective coordinates of the point R on this line, another way of interpreting the process here is the mechanical balancing of moments about an arbitrary point
19.
Frame of reference
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In physics, a frame of reference consists of an abstract coordinate system and the set of physical reference points that uniquely fix the coordinate system and standardize measurements. In n dimensions, n+1 reference points are sufficient to define a reference frame. Using rectangular coordinates, a frame may be defined with a reference point at the origin. In Einsteinian relativity, reference frames are used to specify the relationship between an observer and the phenomenon or phenomena under observation. In this context, the phrase often becomes observational frame of reference, a relativistic reference frame includes the coordinate time, which does not correspond across different frames moving relatively to each other. The situation thus differs from Galilean relativity, where all possible coordinate times are essentially equivalent, the need to distinguish between the various meanings of frame of reference has led to a variety of terms. For example, sometimes the type of system is attached as a modifier. Sometimes the state of motion is emphasized, as in rotating frame of reference, sometimes the way it transforms to frames considered as related is emphasized as in Galilean frame of reference. Sometimes frames are distinguished by the scale of their observations, as in macroscopic and microscopic frames of reference, in this sense, an observational frame of reference allows study of the effect of motion upon an entire family of coordinate systems that could be attached to this frame. On the other hand, a system may be employed for many purposes where the state of motion is not the primary concern. For example, a system may be adopted to take advantage of the symmetry of a system. In a still broader perspective, the formulation of many problems in physics employs generalized coordinates, normal modes or eigenvectors and it seems useful to divorce the various aspects of a reference frame for the discussion below. A coordinate system is a concept, amounting to a choice of language used to describe observations. Consequently, an observer in a frame of reference can choose to employ any coordinate system to describe observations made from that frame of reference. A change in the choice of coordinate system does not change an observers state of motion. This viewpoint can be found elsewhere as well, which is not to dispute that some coordinate systems may be a better choice for some observations than are others. Choice of what to measure and with what observational apparatus is a separate from the observers state of motion. D. Norton, The discussion is taken beyond simple space-time coordinate systems by Brading, extension to coordinate systems using generalized coordinates underlies the Hamiltonian and Lagrangian formulations of quantum field theory, classical relativistic mechanics, and quantum gravity
20.
Washer (hardware)
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A washer is a thin plate with a hole that is normally used to distribute the load of a threaded fastener, such as a screw or nut. Other uses are as a spacer, spring, wear pad, preload indicating device, locking device, Washers usually have an outer diameter about twice larger than their inner diameter. Washers are usually metal or plastic, high-quality bolted joints require hardened steel washers to prevent the loss of pre-load due to Brinelling after the torque is applied. Washers are also important for preventing galvanic corrosion, particularly by insulating steel screws from aluminium surfaces, the origin of the word is unknown, the first recorded use of the word was in 1346, however, the first time its definition was recorded was in 1611. The American National Standards Institute provides standards for general use flat washers, type A is a series of steel washers at broad tolerances, where precision is not critical. Type B is a series of flat washers with tighter tolerances where outside diameters are categorized as narrow, type is not to be confused with form. The British Standard for Metric Series Metal Washers written in 1968 coined the term form, lock washers, locknuts, jam nuts, and thread-locking fluid are ways to prevent vibration from loosening a bolted joint. The term washer is often applied to various types such as those used to seal the control valve in taps. Crush washers are made of a metal such as aluminium or copper and are used to seal fluid or gas connections such as those found in an internal combustion engine. Zinc coating acts as a surface layer that falls victim to corrosive materials before the washers material can be harmed. Cadmium produces a high-quality protective surface but is toxic, both biologically and environmentally, nickel coatings add protection from corrosion only when the finish is dense and non-porous. Electroplating – This method involves coating the washer by electrolytic deposition using metals such as chromium or silver, phosphating – A resilient, but abrasive surface is achieved by incorporating a zinc-phosphate layer and corrosion-protective oil. Browning or bluing – Exposing the washer to a compound or alkali salt solution causes an oxidizing chemical reaction. The integrity of the coating can improved by treating the product with a water-displacing oil. Chemical plating – This technique utilizes a nickel-phosphor alloy that is precipitated onto the surface, creating an extremely corrosion-. Washers of standard sizes are listed in the table below. Measurements in the table refer to the dimensions of the washers as described by the drawing, bit guard Dowel Unified Thread Standard Parmley, Robert. ISBN0070486174 Drawings, designs and discussion of various uses of washers
21.
Center of mass
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The distribution of mass is balanced around the center of mass and the average of the weighted position coordinates of the distributed mass defines its coordinates. Calculations in mechanics are simplified when formulated with respect to the center of mass. It is a point where entire mass of an object may be assumed to be concentrated to visualise its motion. In other words, the center of mass is the equivalent of a given object for application of Newtons laws of motion. In the case of a rigid body, the center of mass is fixed in relation to the body. The center of mass may be located outside the body, as is sometimes the case for hollow or open-shaped objects. In the case of a distribution of separate bodies, such as the planets of the Solar System, in orbital mechanics, the equations of motion of planets are formulated as point masses located at the centers of mass. The center of mass frame is a frame in which the center of mass of a system is at rest with respect to the origin of the coordinate system. The concept of center of mass in the form of the center of gravity was first introduced by the ancient Greek physicist, mathematician, and engineer Archimedes of Syracuse. He worked with simplified assumptions about gravity that amount to a uniform field, in work on floating bodies he demonstrated that the orientation of a floating object is the one that makes its center of mass as low as possible. He developed mathematical techniques for finding the centers of mass of objects of uniform density of various well-defined shapes, Newtons second law is reformulated with respect to the center of mass in Eulers first law. The center of mass is the point at the center of a distribution of mass in space that has the property that the weighted position vectors relative to this point sum to zero. In analogy to statistics, the center of mass is the location of a distribution of mass in space. Solving this equation for R yields the formula R =1 M ∑ i =1 n m i r i, solve this equation for the coordinates R to obtain R =1 M ∭ Q ρ r d V, where M is the total mass in the volume. If a continuous mass distribution has density, which means ρ is constant. The center of mass is not generally the point at which a plane separates the distribution of mass into two equal halves, in analogy with statistics, the median is not the same as the mean. The coordinates R of the center of mass of a system, P1 and P2, with masses m1. The percentages of mass at each point can be viewed as projective coordinates of the point R on this line, another way of interpreting the process here is the mechanical balancing of moments about an arbitrary point
22.
Bob (physics)
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A bob is the weight on the end of a pendulum found most commonly, but not exclusively, in pendulum clocks. The advantage of construction is that it positions the centre of mass close to the physical end of the pendulum. This maximizes the moment of inertia, and minimises the length of pendulum required for a given period, shorter pendulums allow the clock case to be made smaller, and also minimize the pendulums air resistance. Since most of the loss in clocks is due to air friction of the pendulum. Traditionally, a pendulum bob is a flat disk, lens-shaped in section. They are usually made of a metal such as iron or brass. Lead is denser, but is avoided because of its softness. In most pendulum clocks the rate is adjusted by moving the bob up or down on the pendulum rod, moving it up shortens the pendulum, making it beat more quickly, and causing the clock to gain time. In the most common arrangement, the bob is attached to the pendulum with an adjustment nut at the bottom, turning the nut adjusts the height of the bob. But some bobs have levers or dials to adjust the height, in some precision clocks there is a smaller auxiliary weight on a threaded shaft to allow more fine adjustment. Tower clocks sometimes have a tray mounted on the rod, to which small weights can be added or removed. The weight of the bob itself has little effect on the period of the pendulum, however, a heavier bob helps to keep the pendulum moving smoothly until it receives its next push from the clocks escapement mechanism. That increases the pendulums Q factor, making the motion of the more independent of the escapement. On the other hand, the heavier the bob is the energy must be supplied by the clocks power source and more friction. Pendulum bobs in quality clocks are made as heavy as the clocks movement can drive. A common weight for the bob of a one second pendulum, widely used in grandfather clocks and many others, is 15 lbs
23.
Chalk line
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A chalk line or chalk box is a tool for marking long, straight lines on relatively flat surfaces, much farther than is practical by hand or with a straightedge. A chalk line draws straight lines by the action of a nylon or similar string that has been previously coated with a loose dye. The string is then laid across the surface to be marked and pulled tight, next, the string is then plucked or snapped sharply, causing the string to strike the surface, which then transfers its chalk to the surface along that straight line where it struck. Chalk lines are used to mark relatively flat surfaces. However, as long as the line is taut and the two ends of the line are in nearly the same plane, the chalk line will mark all points that the string touches on or near that plane once snapped. The objects to be marked do not need to be continuous along the line, Chalk lines can also be used across irregular surfaces and surfaces with holes in them, for example on an unfinished stud wall. The primary problems associated with maintenance of a chalk line are string breakage due to excessive tension on the line. Chalk lines and plumb-bobs are often sold as a single tool, Chalk lines have been in use since ancient Egypt, and used continuously by builders in various cultures since. Continuing development of simple but effective tool focuses on the coloration for the chalk or marking compound, as well as the outer case. In East Asia, an ink line is used in preference to a chalk line and this is a silken cord, stored on a combined reel and inkpot called a sumitsubo in Japanese. Alongside the line reel is a cavity filled with ink-soaked cotton fibres and these sumitsubo are highly decorated and much-prized by their owners. As with many tools, theyre often made by their users while apprentices. On the completion of a building, such as a temple. As part of event, a set of symbolic carpenters tools are freshly made. A sumitsubo is a tool included with them. Measuring tape Chalk line – One person operation Chalk line – Two-person operation Hand-made chalk-line
24.
Horizontal and vertical
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The usage of the inter-related terms horizontal and vertical as well as their symmetries and asymmetries vary with context. In astronomy, geography, and related sciences and contexts, a passing by a given point is said to be vertical if it is locally aligned with the local gravity vector at that point. In general, something that is vertical can be drawn from up to down, girard Desargues defined the vertical to be perpendicular to the horizon in his Perspective of 1636. The word horizontal is derived from horizon, whereas vertical originates in the late Latin verticalis, in the context of a two-dimensional orthogonal Cartesian coordinate system on a Euclidean plane, to say that a line is horizontal or vertical, an initial designation has to be made. One can start off by designating the vertical direction, usually labelled the Y direction, the horizontal direction, usually labelled the X direction, is then automatically determined. Or, one can do it the way around, i. e. nominate the x-axis. There is no reason to choose the horizontal over the vertical as the initial designation. The following hold in the case, a) Through any point P in the plane, there is one and only one vertical line within the plane and one. This symmetry breaks down as one moves to the three-dimensional case, b) A vertical line is any line parallel to the vertical direction. A horizontal line is any line normal to a vertical line, c) Horizontal lines do not cross each other. D) Vertical lines do not cross each other, not all of these elementary geometric facts are true in the 3-D context. In the three-dimensional case, the situation is complicated as now one has horizontal and vertical planes in addition to horizontal and vertical lines. Consider a point P and designate a direction through P as vertical, a plane which contains P and is normal to the designated direction is the horizontal plane at P. Any plane going through P, normal to the plane is a vertical plane at P. Through any point P, there is one and only one horizontal plane and this is a new feature that emerges in three dimensions. The symmetry that exists in the case no longer holds. In physics, in engineering, and in construction, the designated as vertical is usually that along which a plumb-bob hangs. Alternatively, a level that exploits the buoyancy of an air bubble
25.
International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
26.
Scale ruler
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An architects scale is a specialized ruler designed to facilitate the drafting and measuring of architectural drawings, such as floor plans and orthographic projections. Because the scale of such drawings are often smaller than life-size, for accuracy and longevity, the material used should be dimensionally stable and durable. Scales were traditionally made of wood, but today they are made of rigid plastic or aluminium. Architects scales may be flat, with 4 scales, or have a symmetric 3-lobed cross-section, in the United States, and prior to metrification in Britain, Canada and Australia, architects scales are/were marked as a ratio of x inches-to-the-foot. It is not to be confused with a true unitless ratio -- a 1,5 architectural scale would be a 1,60 unitless scale, therefore, a drawing will indicate both its scale and the unit of measurement being used. In Britain, and elsewhere, the units used on architectural drawings are the units millimetres and metres. In Britain, for rulers, the paired scales often found on architects scales are, For triangular rulers
27.
Beam compass
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A beam compass is a compass with a beam and sliding sockets or cursors for drawing and dividing circles larger than those made by a regular pair of compasses. The instrument can be as a whole, or made on the spot with individual sockets, a draftsmans beam compass consists of a set of points and holders, mounted on a plated brass, aluminum, or electrum rod. One end is generally locked down at the end of the rod, the locked tip holder consists of a needle, for the center of the radius, and the other holds either a lead clutch, or an inking nib. There are older variants which use a wooden beam, another similar type is a Machinist or Engineers beam compass, which uses scribing points only, similar to ones used by woodworkers, except that its fine adjustment is generally more refined. These beam compasses can be extended by adding press-in rods, or by using a lockable rod connector, trammels or trammel points are the sockets or cursors that, together with the beam, make up a beam compass. Their relatively small size makes them easy to store or transport and they consist of two separate metal pieces that are usually connected by a piece of wood, The wood timber is not included in the purchase of the trammel points. It can be ripped on a table saw, a lumber yard or woodworking store should have a piece readily available to fit the opening also, metal, or pipe. They work like a scratch awl, as for any compass, there are two uses. The beam compass is used to scribe a circle, either by drawing with lead, penning by ink, the radius can be adjusted by sliding the metal point holder across a wood beam or metal rod, and locking it by turning a knob at the desired location. Some have a fine radius adjustment, the threaded adjustment is similar to that of a Screw. The only limitation is the rigidity of the beam or metal rod being used. Longer wooden beams tend to sag depending on the species of wood used, metal rods can be used as an alternative, but they also have length limitations. Some trammel sets include a support roller for attachment at mid span of the beam or rod, trammel points score a precise line by using a sharpened point, or draw a line using a lead clutch, or an ink nib. When the circular knob is turned, it micro adjusts the radius of the circle, on some, a spring and screw mechanism locks the compass at the precise desired location. Turning clockwise decreases the radius while turning increases the radius slightly. A beam compass can also be used to make a series of measurements in a precise manner. Each point is rotated 180° along a line or large circle. The indentation created by the point of the trammel is easily seen
28.
Calipers
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A caliper is a device used to measure the distance between two opposite sides of an object. A caliper can be as simple as a compass with inward or outward-facing points. The tips of the caliper are adjusted to fit across the points to be measured, the caliper is then removed and it is used in many fields such as mechanical engineering, metalworking, forestry, woodworking, science and medicine. A plurale tantum sense of the word calipers coexists in natural usage with the regular noun sense of caliper, also existing colloquially but not in formal usage is referring to a vernier caliper as a vernier or a pair of verniers. In imprecise colloquial usage, some extend this even to dial calipers. In machine-shop usage, the caliper is often used in contradistinction to micrometer. In this usage, caliper implies only the factor of the vernier or dial caliper. The earliest caliper has been found in the Greek Giglio wreck near the Italian coast, the ship find dates to the 6th century BC. The wooden piece already featured a fixed and a movable jaw, although rare finds, caliper remained in use by the Greeks and Romans. A bronze caliper, dating from 9 AD, was used for minute measurements during the Chinese Xin dynasty, the caliper had an inscription stating that it was made on a gui-you day at new moon of the first month of the first year of the Shijian guo period. The calipers included a slot and pin and graduated in inches, the modern vernier caliper, reading to thousandths of an inch, was invented by American Joseph R. Brown in 1851. It was the first practical tool for exact measurements that could be sold at a price within the reach of ordinary machinists, the inside calipers are used to measure the internal size of an object. The upper caliper in the image requires manual adjustment prior to fitting, fine setting of this caliper type is performed by tapping the caliper legs lightly on a handy surface until they will almost pass over the object. A light push against the resistance of the pivot screw then spreads the legs to the correct dimension and provides the required. The lower caliper in the image has a screw that permits it to be carefully adjusted without removal of the tool from the workpiece. Outside calipers are used to measure the size of an object. The same observations and technique apply to this type of caliper, with some understanding of their limitations and usage, these instruments can provide a high degree of accuracy and repeatability. They are especially useful when measuring over very large distances, consider if the calipers are used to measure a large diameter pipe, a vernier caliper does not have the depth capacity to straddle this large diameter while at the same time reach the outermost points of the pipes diameter
29.
Combination square
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A combination square is a tool used for multiple purposes in woodworking, stonemasonry and metalworking. It is composed of a blade and one or more interchangeable heads that may be affixed to it. The most common head is the standard or square head which is used to lay out or check right, invented in 1883 by Laroy S. Starrett, the combination square continues to be a commonplace tool in home workshops, construction jobsites and metalworking. Measuring angles — A combination square can reliably measure 90° and 45° angles, the 45° angle is used commonly in creating miter joints. Determining flatness — When working with wood the first step is to designate a reference surface on a board which is known as the face side, the rest of the workpiece is measured from the face side Measuring the center of a circular bar or dowel. Perform this action at two locations and the lines will approximate the center of the bar. Protractor head allows angles to be set and measured between the base and ruler, a rudimentary level for approximating level surfaces is incorporated in the protractor and also the 45° holder. By moving and setting the head, it can be used as a gauge or to transfer dimensions. Marking the work surface, with the included Scribe Point stored in a hole in the Square Base. It is used to find the center of the round jobs, in woodworking, the starting raw material is neither flat nor square, however, the end product such as a table must be flat and have corners and legs which are square. In metalworking, it is useful for a variety of layout. When used correctly, a high degree of precision can be achieved. One use would be setting large items at the angle in machine vices
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Compass (drawing tool)
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A pair of compasses, also known simply as a compass, is a technical drawing instrument that can be used for inscribing circles or arcs. As dividers, they can also be used as tools to measure distances, Compasses can be used for mathematics, drafting, navigation and other purposes. Compasses are usually made of metal or plastic, and consist of two connected by a hinge which can be adjusted to allow the changing of the radius of the circle drawn. Typically one part has a spike at its end, and the part a pencil. Prior to computerization, compasses and other tools for manual drafting were often packaged as a bow set with interchangeable parts, today these facilities are more often provided by computer-aided design programs, so the physical tools serve mainly a didactic purpose in teaching geometry, technical drawing, etc. Compasses are usually made of metal or plastic, and consist of two connected by a hinge which can be adjusted to allow the changing of the radius of the circle drawn. Typically one part has a spike at its end, and the part a pencil. The handle is usually half a inch long. Users can grip it between their pointer finger and thumb, there are two types of legs in a pair of compasses, the straight or the steady leg and the adjustable one. Each has a purpose, the steady leg serves as the basis or support for the needle point. The screw on your hinge holds the two legs in its position, the hinge can be adjusted depending on desired stiffness, the tighter the screw the better the compass’ performance. The needle point is located on the leg, and serves as the center point of circles that are drawn. The pencil lead draws the circle on a paper or material. This holds the lead or pen in place. Circles can be made by fastening one leg of the compasses into the paper with the spike, putting the pencil on the paper, the radius of the circle can be adjusted by changing the angle of the hinge. Distances can be measured on a map using compasses with two spikes, also called a dividing compass, to use a pair of compasses, place the points on a ruler and open it to the measurement of ½ of the measurement of the circle that is desired. For instance, if one desires to draw a 3 inch circle, next, place the point on the spot that you wish the center of your circle to be, and then rotate the section that has the pencil lead around the point, using the handle. Compasses-and-straightedge constructions are used to illustrate principles of plane geometry, although a real pair of compasses is used to draft visible illustrations, the ideal compass used in proofs is an abstract creator of perfect circles
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Coordinate-measuring machine
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A coordinate measuring machine is a device for measuring the physical geometrical characteristics of an object. This machine may be controlled by an operator or it may be computer controlled. Measurements are defined by an attached to the third moving axis of this machine. Probes may be mechanical, optical, laser, or white light, a machine which takes readings in six degrees of freedom and displays these readings in mathematical form is known as a CMM. The typical 3D bridge CMM is composed of three axes, X, Y and Z and these axes are orthogonal to each other in a typical three-dimensional coordinate system. Each axis has a system that indicates the location of that axis. The machine reads the input from the probe, as directed by the operator or programmer. By precisely recording the X, Y, and Z coordinates of the target and these points are collected by using a probe that is positioned manually by an operator or automatically via Direct Computer Control. The material used to construct the frame has varied over the years. Granite and steel were used in the early CMMs, today all the major CMM manufacturers build frames from aluminium alloy or some derivative and also use ceramic to increase the stiffness of the Z axis for scanning applications. Few CMM builders today still manufacture granite frame CMM due to market requirement for improved metrology dynamics, typically only low volume CMM builders and domestic manufacturers in China and India are still manufacturing granite CMM due to low technology approach and easy entry to become a CMM frame builder. The increasing trend towards scanning also requires the CMM Z axis to be stiffer and new materials have been introduced such as ceramic, Probing system Data collection and reduction system - typically includes a machine controller, desktop computer and application software. These machines can be free-standing, handheld and portable, the first 3-axis models began appearing in the 1960s and computer control debuted in the early 1970s. Leitz Germany subsequently produced a fixed machine structure with moving table, in modern machines, the gantry type superstructure has two legs and is often called a bridge. This moves freely along the table with one leg following a guide rail attached to one side of the granite table. The opposite leg simply rests on the table following the vertical surface contour. Air bearings are the method for ensuring friction free travel. In these, compressed air is forced through a series of small holes in a flat bearing surface to provide a smooth
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Drafting machine
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A drafting machine is a tool used in technical drawing, consisting of a pair of scales mounted to form a right angle on an articulated protractor head that allows an angular rotation. The protractor head is able to move freely across the surface of the drawing board and these guides, which act separately, ensure the movement of the set in the horizontal or vertical direction of the drawing board, and can be locked independently of each other. The drafting machine was invented by Charles H, little in 1901, and he founded the Universal Drafting Machine Company in Cleveland, Ohio, to manufacture and sell the instrument. Drafting machines were present in the offices of European companies since the 1920s. In the older sets, the movement of the protractor head was assured by a pantograph system that could keep the head in the same angular position throughout its range of motion. The arms were balanced by a system of counterweights or springs, typically, the machine is mounted on a drawing board with a hard and smooth surface, anchored to a base that allows its tilting and lifting. Thus, the realization of a drawing can be achieved in the most convenient way on a surface that can be tilted at any angle from horizontal to vertical. There are special versions for A0 double-sized boards, to make drawings, or copying-boards with background illumination
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Flat spline
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Before computers were used for creating engineering designs, drafting tools were employed by designers drawing by hand. To draw curves, especially for shipbuilding, draftsmen often used long, thin, flexible strips of wood, plastic, the splines were held in place with lead weights. Splines are more recently referred to as flexible curves and perform much of the original function, the main difference between splines and flexible curves is that the control points of flexible curves are entirely internal in their housing. One can recreate an original draftsmans spline device with weights and a length of thin plastic or rubber tubing. The weights are attached to the tube, the tubing is then placed over drawing paper. Crosses are marked on the paper to designate the knots or control points, the tube is then adjusted so that it passes over the control points. In 1946, mathematicians started studying the shape and derived the piecewise polynomial formula known as the spline curve. This has led to the use of such functions in computer-aided design. I. J. Schoenberg gave the spline function its name after its resemblance to the mechanical spline used by draftsmen, the origins of the spline in wood-working may show in the conjectured etymology, which connects the word spline to the word splinter. Later craftsmen have made out of rubber, steel. Spline devices help bend the wood for pianos, violins, violas, the Wright brothers used one to shape the wings of their aircraft. Lesbian rule French curve Technical drawing tools
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French curve
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A French curve is a template usually made from metal, wood or plastic composed of many different curves. It is used in manual drafting to draw smooth curves of varying radii, the shapes are segments of the Euler spiral or clothoid curve. The curve is placed on the material, and a pencil. As modern computer-aided design systems use vector-based graphics to achieve a precise radius, flat spline Lesbian rule Technical drawing tools Weisstein, Eric W. French Curve from MathWorld. Use of the French Curve from Integrated Publishing
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Gunter's chain
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Gunters chain or the surveyors chain is a distance measuring device used for land survey. Gunter used an actual measuring chain of 100 links and these, the chain and the link, have become units of their own. The 66-foot chain is divided into 100 links, usually marked off into groups of 10 by brass rings or tags which simplify intermediate measurement, each link is thus 7.92 inches long. Gunters chain reconciled two seemingly incompatible systems, the traditional English land measurements, based on the number 4, the surveyor is assisted by a chainman. A ranging rod is placed in the ground at the destination point. A pin is put in the ground at the end of the chain, and the chain is moved forward so that its hind end is at that point. The whole process is repeated for all the pairs of points required. The process is surprisingly accurate and requires very low technology. Surveying with a chain is simple if the land is level and continuous—it is not physically practicable to range across large depressions or significant waterways, for example. On sloping land, the chain was to be leveled by raising one end as needed, although Gunters chain was later superseded by the steel tape, its legacy was a new unit of length called the chain, which measured 66 feet. This unit still exists as a location identifier on British railways, in the United States, for example, Public Lands Survey plats are published in the chain unit to maintain the consistency of a two-hundred-year-old database. Minor roads surveyed in Australia and new Zealand were in the 19th, in some places other lengths have been used, for example 8.928 inches in Scotland and 10.08 inches in Ireland. The length of a pitch is exactly one chain. A similar American system, of lesser popularity, is Ramsden’s or the engineer’s system, the original of such chains was that constructed, to very high precision, for the measurement of the baselines of the Anglo-French Survey and the Principal Triangulation of Great Britain. The even less common Rathborn system, also from the 17th century, is based on a 200-link chain of two rods length, each rod consists of 100 links, which are called seconds, ten of which make a prime. Vincent Wing made chains with 9. 90-inch links, most commonly as 33-foot half-chains of 40 links and these chains were sometimes used in the American colonies, particularly Pennsylvania. Distance measurement How to make a Gunters Chain Image from 1675 Nineteenth century image
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Laser line level
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A laser line level is a tool combining a spirit level and/or plumb bob with a laser to display an accurately horizontal or vertical illuminated line on a surface the laser line level is laid against. Laser line levels are used wherever accurate verticals and horizontals are required, typically in the construction, some models are inexpensive enough for do-it-yourself applications. The laser beam is fanned to produce a thin plane beam accurately horizontal or vertical, a more advanced device may be accurate to within 0.3 mm/m, while lower-end models may be closer to 1.5 mm/m. The illuminated line is necessarily absolutely straight, so that the level can be used as a straightedge, for example, to see if a shelf is warped. Dumpy level Theodolite List of laser articles Laser Machine Control Checking a level for accuracy
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Laser rangefinder
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A laser rangefinder is a rangefinder which uses a laser beam to determine the distance to an object. Due to the speed of light, this technique is not appropriate for high precision sub-millimeter measurements. The pulse may be coded to reduce the chance that the rangefinder can be jammed and it is possible to use Doppler effect techniques to judge whether the object is moving towards or away from the rangefinder, and if so, how fast. The precision of the instrument is determined by the rise or fall time of the laser pulse, one that uses very sharp laser pulses and has a very fast detector can range an object to within a few millimeters. Some of the light might reflect off leaves or branches which are closer than the object, giving an early return. All these effects have to be taken into account, the distance between point A and B is given by D = c t 2 where c is the speed of light in the atmosphere and t is the amount of time for the round-trip between A and B. T = φ ω where φ is the delay made by the light traveling. Time of flight - this measures the time taken for a pulse to travel to the target. With the speed of light known, and a measurement of the time taken. Many pulses are fired sequentially and the response is most commonly used. This technique requires very accurate sub-nanosecond timing circuitry, multiple frequency phase-shift - this measures the phase shift of multiple frequencies on reflection then solves some simultaneous equations to give a final measure. Interferometry - the most accurate and most useful technique for measuring changes in distance rather than absolute distances, rangefinders provide an exact distance to targets located beyond the distance of point-blank shooting to snipers and artillery. They can also be used for military reconciliation and engineering, handheld military rangefinders operate at ranges of 2 km up to 25 km and are combined with binoculars or monoculars. When the rangefinder is equipped with a magnetic compass and inclinometer it is capable of providing magnetic azimuth, inclination. Some rangefinders can also measure a targets speed in relation to the observer, some rangefinders have cable or wireless interfaces to enable them to transfer their measurement data to other equipment like fire control computers. Some models also offer the possibility to use night vision modules. Most handheld rangefinders use standard or rechargeable batteries, the more powerful models of rangefinders measure distance up to 25 km and are normally installed either on a tripod or directly on a vehicle or gun platform. In the latter case the module is integrated with on-board thermal, night vision
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Measuring rod
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A measuring rod is a tool used to physically measure lengths and survey areas of various sizes. Most measuring rods are round or square sectioned, however they can be flat boards, some have markings at regular intervals. It is likely that the rod was used before the line. The oldest preserved measuring rod is a bar which was found by the German Assyriologist Eckhard Unger while excavating at Nippur. The bar dates from c.2650 BC. and Unger claimed it was used as a measurement standard, measuring rods for different purposes and sizes have been found from China and elsewhere dating to the early 2nd millennium B. C. E. Cubit-rods of wood or stone were used in Ancient Egypt, fourteen of these were described and compared by Lepsius in 1865. Flinders Petrie reported on a rod that shows a length of 520.5 mm, a slate measuring rod was also found, divided into fractions of a Royal Cubit and dating to the time of Akhenaten. Further cubit rods have been found in the tombs of officials, two examples are known from the tomb of Maya—the treasurer of the 18th dynasty pharaoh Tutankhamun—in Saqqara. Another was found in the tomb of Kha in Thebes and these cubits are ca 52.5 cm long and are divided into seven palms, each palm is divided into four fingers and the fingers are further subdivided. Another wooden cubit rod was found in Theban tomb TT40 bearing the name of Tutankhamun. Egyptian measuring rods also had marks for the Remen measurement of approximately 370mm, used in construction of the Pyramids. A hazel measuring rod recovered from a Bronze Age burial mound in Borum Eshøj, the megalithic structures of Great Britain has been hypothesized to have been built by a Megalithic Yard, though some authorities believe these structures have been measured out by pacing. Several tentative Bronze age bone fragments have been suggested as being parts of a rod for this hypothetical measurement. Republican Rome used several measures, including the various Greek feet measurements, standardisation was introduced by Agrippa in 29 BC, replacing all previous measurements by a Roman foot of 29.6 cm, which became the foot of Imperial Rome. The Roman measuring rod was 10 Roman feet long, and hence called a decempeda and it was usually of square section capped at both ends by a metal shoe, and painted in alternating colours. Together with the groma and Dioptra the decempeda formed the basic kit for the Roman surveyors, the measuring rod is frequently found depicted in Roman art showing the surveyors at work. A shorter folding yardstick one Roman foot long is known from excavations of a Roman fort in Niederburg, in the Middle Ages, bars were used as standards of length when surveying land. These bars often used a unit of measure called a rod, of equal to 5.5 yards,5.0292 metres,16.5 feet
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Micrometer
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Micrometers are usually, but not always, in the form of calipers, which is why micrometer caliper is another common name. The spindle is a very accurately machined screw and the object to be measured is placed between the spindle and the anvil, the spindle is moved by turning the ratchet knob or thimble until the object to be measured is lightly touched by both the spindle and the anvil. Micrometers are also used in telescopes or microscopes to measure the apparent diameter of celestial bodies or microscopic objects, the micrometer used with a telescope was invented about 1638 by William Gascoigne, an English astronomer. Colloquially the word micrometer is often shortened to mike or mic, the word micrometer is a neoclassical coinage from Greek micros, meaning small, and metron, meaning measure. The Merriam-Webster Collegiate Dictionary says that English got it from French, neither the metre nor the micrometre nor the micrometer as we know them today existed at that time. However, the people of that time did have much need for, and interest in, the word was no doubt coined in reference to this endeavor, even if it did not refer specifically to its present-day senses. In 1844 details of Whitworths workshop micrometer were published and this was described as having a strong frame of cast iron, the opposite ends of which were two highly finished steel cylinders, which traversed longitudinally by action of screws. The ends of the cylinders where they met was of hemispherical shape, one screw was fitted with a wheel graduated to measure to the ten thousandth of an inch. His object was to furnish ordinary mechanics with an instrument which, the micrometer caliper was introduced to the mass market in anglophone countries by Brown & Sharpe in 1867, allowing the penetration of the instruments use into the average machine shop. Brown & Sharpe were inspired by earlier devices, one of them being Palmers design. In 1888 Edward W. Morley added to the precision of micrometric measurements, each type of micrometer caliper can be fitted with specialized anvils and spindle tips for particular measuring tasks. For example, the anvil may be shaped in the form of a segment of screw thread, in the form of a v-block, universal micrometer sets come with interchangeable anvils, such as flat, spherical, spline, disk, blade, point, and knife-edge. The term universal micrometer may also refer to a type of micrometer whose frame has modular components, allowing one micrometer to function as outside mic, depth mic, step mic, blade micrometers have a matching set of narrow tips. They allow, for example, the measuring of a narrow o-ring groove, pitch-diameter micrometers have a matching set of thread-shaped tips for measuring the pitch diameter of screw threads. Limit mics have two anvils and two spindles, and are used like a snap gauge, the part being checked must pass through the first gap and must stop at the second gap in order to be within specification. The two gaps accurately reflect the top and bottom of the tolerance range, bore micrometer, typically a three-anvil head on a micrometer base used to accurately measure inside diameters. Tube micrometers have a cylindrical anvil positioned perpendicularly to a spindle and is used to measure the thickness of tubes. Micrometer stops are micrometer heads that are mounted on the table of a milling machine, bedways of a lathe, or other machine tool
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Protractor
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A protractor is a measuring instrument, typically made of transparent plastic or glass, for measuring angles. Most protractors measure angles in degrees, radian-scale protractors measure angles in radians. Most protractors are divided into 180 equal parts and they are used for a variety of mechanical and engineering-related applications, but perhaps the most common use is in geometry lessons in schools. More advanced protractors, such as the bevel protractor, have one or two swinging arms, which can be used to measure the angle. A bevel protractor is a graduated circular protractor with one pivoted arm used for measuring or marking off angles, sometimes Vernier scales are attached to give more precise readings. It has wide application in architectural and mechanical drawing, although its use is decreasing with the availability of drawing software or CAD. Universal bevel protractors are also used by toolmakers, as they measure angles by mechanical contact they are classed as mechanical protractors, the bevel protractor is used to establish and test angles to very close tolerances. It reads to 5 minutes or 1/12° and can measure any angle from 0° to 360°, the bevel protractor consists of a beam, a graduated dial and a blade which is connected to a swivel plate by thumb nut and clamp. When the edges of the beam and blade are parallel, a mark on the swivel plate coincides with the zero line on the graduated dial. To measure an angle between the beam and the blade of 90° or less, the reading may be obtained direct from the number on the dial indicated by the mark on the swivel plate. To measure an angle of over 90°, subtract the number of degrees as indicated on the dial from 180°, as the dial is graduated from opposite zero marks to 90° each way. Since the spaces, both on the scale and the Vernier scale, are numbered both to the right and to the left from zero, any angle can be measured. The readings can be either to the right or to the left. The above picture illustrates a variety of uses of the bevel protractor, reading the Vernier scale, The bevel protractor Vernier scale may have graduations of 5′ or 1/12°. Each space on the Vernier scale is 5′ less than two spaces on the main scale, twenty four spaces on the Vernier scale equal in extreme length twenty three double degrees. Thus the difference between the occupied by 2° on a main scale and the space of the Vernier scale is equal to one twenty-fourth of 2°. Read off directly from the scale the number of whole degrees between 0 on this scale and the 0 of the Vernier scale. For example, Zero on the scale has moved 28 whole degrees to the right of the 0 on the main scale
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Radius gauge
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A radius gauge, also known as a fillet gauge, is a tool used to measure the radius of an object. Radius gauges require a light behind the object to be measured. The gauge is placed against the edge to be checked and any light leakage between the blade and edge indicates a mismatch that requires correction, a good set of gauges will offer both convex and concave sections, and allow for their application in awkward locations. Every leaf has a different radius, the material of the leaves is stainless steel. It is used to check the radius of inner and outer surfaces, frane, James T. Craftsmans Illustrated Dictionary of Construction Terms, Craftsman Book Company, ISBN 978-1-57218-008-6. Kennedy, Clifford W. Hoffman, Edward G. Bond, inspection and Gaging, Industrial Press Inc
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Ruler
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A ruler, sometimes called a rule or line gauge, is an instrument used in geometry, technical drawing, printing, engineering and building to measure distances or to rule straight lines. The ruler is a straightedge which may also contain calibrated lines to measure distances, rulers have long been made from different materials and in a wide range of sizes. Plastics have also used since they were invented, they can be molded with length markings instead of being scribed. Metal is used for more durable rulers for use in the workshop,12 inches or 30 cm in length is useful for a ruler to be kept on a desk to help in drawing. Shorter rulers are convenient for keeping in a pocket, longer rulers, e. g.18 inches are necessary in some cases. Rigid wooden or plastic yardsticks,1 yard long, and meter sticks,1 meter long, are also used, classically, long measuring rods were used for larger projects, now superseded by tape measure or laser rangefinders. Desk rulers are used for three purposes, to measure, to aid in drawing straight lines and as a straight guide for cutting and scoring with a blade. Practical rulers have distance markings along their edges, a line gauge is a type of ruler used in the printing industry. These may be made from a variety of materials, typically metal or clear plastic, units of measurement on a basic line gauge usually include inches, agate, picas, and points. More detailed line gauges may contain sample widths of lines, samples of common type in several point sizes, measuring instruments similar in function to rulers are made portable by folding or retracting into a coil when not in use. When extended for use, they are straight, like a ruler, the illustrations on this page show a 2-meter carpenters rule, which folds down to a length of 24 cm to easily fit in a pocket, and a 5-meter-long tape, which retracts into a small housing. A flexible length measuring instrument which is not necessarily straight in use is the tailors fabric tape measure and it is used to measure around a solid body, e. g. a persons waist measurement, as well as linear measurement, e. g. inside leg. It is rolled up when not in use, taking up little space, a contraction rule is made having larger divisions than standard measures to allow for shrinkage of a metal casting. They may also be known as a shrinkage or shrink rule, a ruler software program can be used to measure pixels on a computer screen or mobile phone. These programs are known as screen rulers. In geometry, a ruler without any marks on it may be used only for drawing lines between points. A straightedge is used to help draw accurate graphs and tables. A ruler and compass construction refers to using an unmarked ruler
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Set square
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A set square or triangle is an object used in engineering and technical drawing, with the aim of providing a straightedge at a right angle or other particular planar angle to a baseline. The most simple form of set square is a piece of transparent plastic with the centre removed. More commonly the set square bears the markings of a ruler, the outer edges are typically bevelled. These set squares come in two forms, both right triangles, one with 90-45-45 degree angles, the other with 30-60-90 degree angles. Combining the two forms by placing the hypotenuses together will also yield 15° and 75° angles and they are often purchased in packs with protractors and compasses. Less commonly found is the set square. Here, the body of the object is cut in half, adjustment to the marked angle will produce any desired angle up to a maximum of 180°. In many European countries, the most common form of set square combines a 90-45-45 triangle with a protractor into a tool made of clear plastic. Named Geodreieck, it was developed and trademarked by the German manufacturer Aristo-Instrumente Dennert KG in 1964
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Sliding T bevel
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A sliding T bevel, also known as a bevel gauge or false square is an adjustable gauge for setting and transferring angles. The handle is made of wood or plastic and is connected to a metal blade with a thumbscrew or wing nut. The blade pivots and can be locked at any angle by loosening or tightening the thumbscrew, the bevel can be used to duplicate an existing angle, or set to a desired angle by using it with any number of other measuring tools. Bevel Readers Digest Book of Skills & Tools
