weighing machine: see balance; scale.

voting machine, instrument for recording and counting votes. The voting machine itself is generally positioned in a booth, often closed off by a curtain to assure secrecy for the voter.

In the case of older mechanical voting machines, when a voter enters the booth and closes the curtain by means of a lever, the machine unlocks for voting. The titles of all elective offices are listed on the face of the machine along with the party candidates running for each office. Above each name is a lever which, when depressed, indicates a vote for that candidate. Only one candidate for each office may be selected. Write-in votes are possible and propositions are placed at the top of the ballot. When the voter pulls the curtain open to leave, the machine automatically registers the vote and is cleared for use by the next person.

The mecahnical voting machine was first used in New York state in 1892, and came to be used throughout the United States. Faster and more accurate in tabulating the vote than the paper ballot, mechanical voting machines were gradually replaced in many parts of the United States in the late 20th cent. by so-called electronic or computerized voting machines. In one form of electronic voting, voters indicate their preferences using punch cards that are read by computer, but in the United States punch cards fell out of favor after their use led to controversy in the 2000 presidential election. Both lever-type mechanical voting machines and punch-card-based machines were replaced by other systems with federal aid provided under the Help American Vote Act (2002).

Other modern voting technologies include the optical-scan system, in which marked ballots are read by computer using optical sensing, and the direct-record electronic voting system, in which a voter chooses a candidate by means of push buttons or touch screens on a computerized voting machine, which tallies the votes. A number of experts, including the National Institute of Standards and Technology, have called for direct-record electronic systems to have increased safeguards against potential computer tampering and/or to provide a paper record of an individual's vote so that a non-electronic means of recounting a challenged electoral result would exist.

Estonia has used Internet voting, via a website, as an alternative form of voting. Voters use a computer-readable identification card and enter two passwords before they vote. The method was pioneered in local elections in 2005 and used in national elections in 2007.

The voting machine's greatest asset is protection against voting fraud or human error. However, critics claim that it intimidates some citizens, that some machines are subject to breakdown, and that fraud is not completely eliminated. Computerized voting machines that use punch cards are also susceptible to voter error, as they lack the means to prevent a person from voting for two candidates for the same office, and can fail to register a vote clearly.

For many years the United States was the only country that used voting machines extensively; Brazil now uses a national computerized voting system. The cost of voting machines, combined with less frequent elections and simpler ballots in many countries, make them impractical for worldwide use.

vending machine, coin-operated, automatic device for selling goods. Many vending machines are capable of making change, and some of the more sophisticated ones accept paper money or credit cards. The first vending machine was invented by Richard Carlisle, English publisher and bookshop owner, for selling books. Until 1926 vending machines were restricted chiefly to selling penny gum and candy. In that year the invention of a cigarette-vending machine by William Rowe, an American, started a trend toward selling higher-priced merchandise. Soft drink and nickel-candy machines followed in the 1920s and 30s. Today vending machines sell a wide variety of items, e.g., milk, sandwiches, soap, and newspapers. Operators maintain and service machines and pay rent, usually a commission on sales, to the owners of the location sites. Some luncheonettes consist entirely of unattended vending machines.

sewing machine, device that stitches cloth and other materials. An attempt at mechanical sewing was made in England (1790) with a machine having a forked, automatic needle that made a single-thread chain. In 1830, B. Thimonnier, a French tailor, patented a wooden device with a hooked needle. In 1841 he used 80 of these machines to make uniforms for the French army. His factory was wrecked by a mob, but in 1848 he placed another machine on the market. A needle with an eye at its point that made a chain stitch was tried about the same time for glove making. Inventor Walter Hunt of New York City is said to have devised in 1832 a machine using an eye-pointed needle but failed to patent it. American inventor Elias Howe made the first successful machine (1846) using an eye-pointed needle and an intermittent feed. After perfecting various features and defending his patents, he made a fortune from his machine. Before 1850 all machines were operated by hand and the cloth was fed by various clumsy devices, such as a separately moved belt with projecting steel spikes. American inventor A. B. Wilson devised in 1850 an automatic feed and later perfected the four-motion feed, an essential feature of later machines. He also invented the rotary bobbin and hook. American inventor Isaac M. Singer, who is credited with the invention of the foot treadle and the yielding presser foot, finally coordinated previous attempts into the modern machine, gave it a commercial status, and began large-scale manufacturing. Two types of machines, the lockstitch and the chain-stitch, operate on the same principle; an eye-pointed needle, raised and lowered at great speed, pierces the material lying on a steel plate, casting a loop of thread on the underside of the seam. In the lockstitch machine a second thread, fed from a shuttle under the plate, passes through the loop and is interlocked with the upper thread as it is drawn tightly up by the rising needle. In the chain-stitch machine, which uses a single thread, the loop is held under the seam while the needle rises, the cloth is fed forward, and the needle descends again, engaging the loop and drawing it flat under the cloth. Both lockstitch and chain-stitch machines are made in two classes, domestic and industrial. Most domestic machines are the lockstitch type. Electrification and attachments for hemming, tucking, quilting, embroidering, making buttonholes, and similar operations have widened the applications of the household machine; the incorporation of microprocessor controls has allowed domestic machines to perform the kind of highly specialized jobs previously only available on large industrial machines. The sale of patterns and fabrics for domestic sewing remains a significant business. Power-driven, highly specialized machines for industrial use include many used in clothing manufacture, such as those for buttonholing and button sewing, seam finishing, and embroidery. Shoes, gloves, hats, books, upholstery, hosiery, tents, awnings, flags, and sails are sewn on specially devised machines.

perpetual-motion machine, device that would be able to operate continuously and supply useful work, in violation of the laws of thermodynamics. A machine that would produce more energy in the form of work than is supplied to it in the form of heat would violate the first law of thermodynamics, which is a special case of the law of conservation of energy (see conservation laws, in physics), and is known as a perpetual-motion machine of the first kind. A machine that would completely convert heat from a warm body into work, without letting any heat flow into a cooler body, would violate the second law of thermodynamics, which is concerned with entropy changes, and is known as a perpetual-motion machine of the second kind. There were a number of early attempts to design and construct various types of perpetual-motion machines; however, since the 19th cent., when the laws of thermodynamics became understood, most such attempts have been abandoned.

machine translation, in computational linguistics, publishing, and other fields, the use of computers to conduct large-scale translation operations. The electronic translation of one language into another or the electronic syntactic analysis of a text has been attempted since the mid 20th cent. However, the complexities of this type of operation, both practical and theoretical, have resulted in only a limited measure of success.

machine tool, power-operated tool used for finishing or shaping metal parts, especially parts of other machines. An establishment that is equipped with such tools and specializes in such work is known as a machine shop. Machine tools operate by removing material from the workpiece, much as a sculptor works. Basic machining operations are: (1) turning, the shaping of a piece having a cylindrical or conical external contour; (2) facing, the shaping of a flat circular surface; (3) milling, the shaping of a flat or contoured surface; (4) drilling, the formation of a cylindrical hole in a workpiece; (5) boring, the finishing of an existing cylindrical hole, as one formed by drilling; (6) broaching, the production of a desired contour in a surface; (7) threading, the cutting of an external screw thread; and (8) tapping, the cutting of an internal screw thread. In addition there are operations such as sawing, grinding, gear cutting, polishing, buffing, and honing. The tools themselves vary in size from hand-held devices that can be used for drilling and grinding to large stationary tools that perform a number of operations. Many machine tools have a name that indicates their principal function, e.g., drill press, broach machine, milling machine, and jig borer. The lathe can perform turning, facing, threading, drilling, and other operations. In order to withstand the great heat that this work generates, the materials used in machine tools must be extremely hard and durable. Thus, their working surfaces are made of such substances as high-speed steels, sintered carbides, and diamonds. To help dissipate the heat, the area of contact between the working surface and the workpiece is usually lubricated with a fluid that may also improve the finish of the workpiece's surface. Modern machine tools are often numerically or computer controlled; where a human operator can be distracted, and is limited by the speed of human reflexes, a numerically controlled machine is more reliable and accurate. See boring mill.

machine gun: see small arms.

machine, arrangement of moving and stationary mechanical parts used to perform some useful work or to provide transportation. From a historical perspective, many of the first machines were the result of human efforts to improve war-making capabilities; the term engineer at one time had an exclusively military connotation. In the United States the original colonies were not permitted to make or import machine tools; it was only after the Revolution that the first manufacturing machines were built (c.1790) by Samuel Slater for a textile mill in Pawtucket, R.I.

Types of Machines

By means of a machine an applied force is increased, its direction is changed, or one form of motion or energy is changed into another form. Thus defined, such simple devices as the lever, the pulley, the inclined plane, the screw, and the wheel and axle are machines. They are called simple machines; more complicated machines are merely combinations of them. Of the five, the lever, the pulley, and the inclined plane are primary; the wheel and axle and the screw are secondary. The wheel and axle combination is a rotary lever, while the screw may be considered an inclined plane wound around a core. The wedge is a double inclined plane.

Complex machines are designated, as a rule, by the operations they perform; the complicated devices used for sawing, planing, and turning, for example, are known as sawing machines, planing machines, and turning machines respectively and as machine tools collectively. Machines used to transform other forms of energy (as heat) into mechanical energy are known as engines, i.e. the steam engine or the internal-combustion engine. The electric motor transforms electrical energy into mechanical energy. Its operation is the reverse of that of the electric generator, which transforms the energy of falling water or steam into electrical energy.

Mechanical Advantage and Efficiency of Machines

By means of a machine, a small force, or effort, can be applied to move a much greater resistance, or load. In doing so, however, the applied force must move through a much greater distance than it would if it could move the load directly. The mechanical advantage (MA) of a machine is the factor by which it multiplies any applied force. The MA may be calculated from the ratio of the forces involved or from the ratio of the distances through which they move. Ideally, the two ratios are equal, and it is simpler to calculate the ratio of the distance the effort moves to the distance the resistance moves; this is called the ideal mechanical advantage (IMA). In any real machine some of the effort is used to overcome friction. Thus, the ratio of the resistance force to the effort, called the actual mechanical advantage (AMA), is less than the IMA.

The efficiency of any machine measures the degree to which friction and other factors reduce the actual work output of the machine from its theoretical maximum. A frictionless machine would have an efficiency of 100%. A machine with an efficiency of 20% has an output only one fifth of its theoretical output. The efficiency of a machine is equal to the ratio of its output (resistance multiplied by the distance it is moved) to its input (effort multiplied by the distance through which it is exerted); it is also equal to the ratio of the AMA to the IMA. This does not mean that low-efficiency machines are of limited use. An automobile jack, for example, must overcome a great deal of friction and therefore has low efficiency, but it is extremely valuable because small effort can be applied to lift a great weight.

Although most machines are used to multiply an effort so that it may move a greater resistance, they may have other purposes. For example, a single, fixed pulley merely changes the direction of the applied force; the pulley may make it easier to lift the load, since a person can pull down on a rope, thus adding his or her own weight to the effort, rather than simply lifting the load. In a catapult an effort greater than the load moves through a short distance, causing the load to be moved through a large distance before being released. As the load is being moved, it picks up speed so that it is traveling at a considerable velocity when it leaves the catapult.

hydraulic machine, machine that derives its power from the motion or pressure of water or some other liquid.

Hydraulic Engines

Water falling from one level to a lower one is used to drive machines like the water wheel and the turbine. The difference in height between the highest and the lowest level is called the head. The amount of work produced per pound of falling water is proportional to the head. Water power can be produced in this way from many natural sources, such as waterfalls and dammed rivers. Where no natural sources are available, an artificial reservoir can be made. When energy is plentiful, it is used to pump water into the reservoir; the water is then available as a power source to drive turbines when energy becomes scarce.

In driving certain industrial hydraulic machines an apparatus called an accumulator is employed to supply high power for short periods of time. One type consists essentially of a cylinder enclosing a piston loaded with weights. When water is slowly pumped into the cylinder, the piston and weights are forced up to a position where they are held. When they are released, they force the water out of the cylinder rapidly, providing the machine with hydraulic power.

Hydrostatic Devices

Water or oil under pressure is commonly used as a source of power for many types of presses, riveting machines, capstans, winches, and other machines. The hydraulic press, or hydrostatic press, was invented by Joseph Bramah and is therefore sometimes called the Bramah press. It consists essentially of two cylinders each filled with liquid and each fitted with a piston; the cylinders are connected by a pipe also filled with the liquid. One cylinder is of small diameter, the other of large diameter. According to Pascal's law, pressure exerted on the smaller piston is transmitted undiminished through the liquid to the surface of the larger piston, which is forced upward. Although the pressure (force per unit of area) is the same for both pistons, the total upward force on the larger piston is as many times greater than the force on the smaller piston as the area of the larger piston is greater than the area of the smaller piston. If, for example, the smaller piston has an area of 2 sq in. and a force of 100 lb is exerted on it, then the force on the larger piston having an area of 50 sq in. would be 2,500 lb (100×50/2=2,500). However, when the pistons move, the distance the smaller piston travels is proportionately greater than the distance the larger piston travels, satisfying the law of conservation of energy. If the smaller piston moves 25 in., the larger one will only move 1 in. The hydraulic press is used, for example, to form three-dimensional objects from sheet metal and plastics and to compress large objects.

The hydraulic jack, also an application of Pascal's law, is used to exert large forces or to lift heavy loads. Like the hydraulic press it consists essentially of two different-sized pistons contained in cylinders that are connected by a pipe. When the smaller piston is moved back and forth by a handle connected to it, it pumps a liquid into the cylinder of the larger piston, forcing the larger piston to move. In this way a weak force applied to the smaller piston can raise a heavy load on the larger one. The hydraulic elevator is also an application of Pascal's law.

heart-lung machine, device that maintains the circulation of the blood and the oxygen content of the body when connected with the arteriovenous system; it is also called the pump oxygenator. The machine is used in open-heart surgery when it is necessary to effect a bypass of the circulatory system of the heart and lungs. The oxygenator repeatedly draws off the blood from the veins, reoxygenates it, and pumps it into the arterial system. The contractions of the heart are halted by running a potassium citrate solution through the coronary vessels. The surgeon is thus enabled to open the heart and make the necessary repairs while the heart is still and his view is not obstructed by blood.

ground-effect machine: see air-cushion vehicle.

gadding machine: see quarrying.

automated teller machine (ATM), device used by bank customers to process account transactions. Typically, a user inserts into the ATM a special plastic card that is encoded with information on a magnetic strip. The strip contains an identification code that is transmitted to the bank's central computer by modem. To prevent unauthorized transactions, a personal identification number (PIN) must also be entered by the user using a keypad. The computer then permits the ATM to complete the transaction; most machines can dispense cash, accept deposits, transfer funds, and provide information on account balances. Banks have formed cooperative, nationwide networks so that a customer of one bank can use an ATM of another for cash access; by 1997 there were more than 160,000 ATMs across the United States. Some ATMs will also accept credit cards for cash advances. The first ATM was installed in 1969 by Chemical Bank at its branch in Rockville Centre, N.Y. A customer using a coded card was dispensed a package containing a set sum of money.

adding machine: see calculator.

Turing machine, a mathematical model of a device that computes via a series of discrete steps and is not limited in use by a fixed maximum amount of data storage. Introduced by the British mathematician Alan Turing in 1936, a Turing machine is a particularly simple computer, one whose operations are limited to reading and writing symbols on tape, or moving along the tape to the left or to the right one symbol at a time. Its behavior at a given moment is determined by the symbol in the square currently being read and by the current state of the machine. The theoretical prototype of the electronic digital computer, Turing machines are one of the key abstractions used in modern computability theory, the study of what computers can and cannot do. Appropriate Turing machines have found application in the study of artificial intelligence, the structure of languages, and pattern recognition.

Machine from which various goods may be purchased, either with coin, paper currency, or electronic payment card. The first vending machines were introduced in 18th-century England to sell snuff and tobacco. From the late 19th century they have been widely used in many countries. Vending service is typically provided by a company that owns the machines and places them in businesses, schools, and the like. These operators provide the products and service either without cost to the owner of the premises on which a machine is located or in return for a servicing charge.

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Machine for stitching material (such as cloth or leather), usually having a needle and shuttle to carry thread and powered by treadle or electricity. Invented by Elias Howe in 1846 and successfully manufactured by Howe and Isaac Merritt Singer, it became the first widely distributed mechanical home appliance and has also been an important industrial machine. Modern sewing machines are usually powered by an electric motor, but the foot-treadle machine is still in wide use in much of the world.

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Machine tool for cutting up bars of material or for cutting out shapes in plates of raw material. The cutting tools (saws) may be thin metallic disks with teeth on their edges, thin metal blades or flexible bands with teeth on one edge, or thin grinding wheels. The tools may use any of three actions: true cutting, grinding, or friction-created melting.

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In U.S. politics, a political organization that controls enough votes to maintain political and administrative control of its community. The rapid growth of cities in the 19th century created huge problems for city governments, which were often poorly organized and unable to provide services. Enterprising politicians were able to win support by offering favours, including patronage jobs and housing, in exchange for votes. Though machines often helped to restructure city governments to the benefit of their constituents, they just as often resulted in poorer service (when jobs were doled out as political rewards), corruption (when contracts or concessions were awarded in return for kickbacks), and aggravation of racial or ethnic hostilities (when the machine did not reflect the city's diversity). Reforms, suburban flight, and a more mobile population with fewer ties to city neighbourhoods have weakened machine politics. Famous machines include those of William Magear Tweed (New York), James Michael Curley (Boston), Thomas Pendergast (Kansas City, Mo.), and Richard J. Daley (Chicago). Seealso civil service.

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Device for producing copies of text or graphic material by the use of light, heat, chemicals, or electrostatic charge. Most modern copiers use a method called xerography.

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Machine tool that rotates a circular tool with numerous cutting edges arranged symmetrically about its axis, called a milling cutter. The metal workpiece is usually held in a vise clamped to a table that can move in three perpendicular directions. Cutters of many shapes and sizes are available for a wide variety of milling operations. Milling machines cut flat surfaces, grooves, shoulders, inclined surfaces, dovetails, and T-slots. Various form-tooth cutters are used for cutting concave forms and convex grooves, for rounding corners, and for cutting gear teeth.

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Stationary, power-driven machine used to cut, shape, or form materials such as metal and wood. Machine tools date from the invention of the steam engine in the 18th century; most common machine tools were designed by the middle of the 19th century. Today dozens of different machine tools are used in the workshops of home and industry. They are frequently classified into seven types: turning machines such as lathes; shapers and planers; power drills or drill presses; milling machines; grinding machines; power saws; and presses (e.g., punch presses).

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Lightweight automatic small-arms weapon chambered for relatively low-energy pistol cartridges and fired from the hip or shoulder. Submachine guns usually have box-type magazines that hold 10–50 cartridges, or occasionally drums holding more rounds. A short-range weapon, they are rarely effective at more than 200 yards (180 m). They can fire 650 or more rounds per minute and weigh 6–10 lbs (2.5–4.5 kg). Important types include the Thompson submachine gun, or tommy gun (patented 1920), the British Sten gun of World War II, and the later Israeli Uzi.

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Automatic weapon capable of rapid, sustained fire, usually 500–1,000 rounds per minute. Developed in the late 19th century by such inventors as Hiram Maxim, it profoundly altered modern warfare. The World War I battlefield was dominated by the belt-fed machine gun, which remained little changed into World War II. Modern machine guns are classified into three groups: the squad automatic weapon, chambered for small-calibre assault-rifle ammunition and operated by one soldier; the general-purpose machine gun, firing full-power rifle ammunition and operated by two; and the heavy machine gun, firing rounds of 12.7 mm (.5 in) or higher and often mounted on an armoured vehicle. Seealso submachine gun.

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Device that amplifies or replaces human or animal effort to accomplish a physical task. A machine may be further defined as a device consisting of two or more parts that transmit or modify force and motion in order to do work. The five simple machines are the lever, the wedge, the wheel and axle, the pulley, and the screw; all complex machines are combinations of these basic devices. The operation of a machine may involve the transformation of chemical, thermal, electrical, or nuclear energy into mechanical energy, or vice versa. All machines have an input, an output, and a transforming or modifying and transmitting device. Machines that receive their input energy from a natural source (such as air currents, moving water, coal, petroleum, or uranium) and transform it into mechanical energy are known as prime movers; examples include windmills, waterwheels, turbines, steam engines, and internal-combustion engines.

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or hovercraft

Vehicle supported above the surface of land or water by an air cushion, produced by downwardly directed fans, enclosed within a flexible skirt beneath the hull. The concept was first proposed by John Thornycroft in the 1870s, but a working model was not produced until 1955, when Christopher Cockerell solved the problem of keeping the air cushion from escaping from under the vehicle, and formed Hovercraft Ltd. to manufacture prototypes. Problems with skirt design and engine maintenance have restricted the vehicle's commercial application; today hovercraft are used mainly as ferries.

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Machine tool that uses a rotating abrasive grinding wheel to change the shape or dimensions of a hard, usually metallic, workpiece. Grinding is the most accurate of all the basic machining processes. All grinding machines use a wheel made from one of the manufactured abrasives, silicon carbide or aluminum oxide. To grind a cylindrical form, the workpiece rotates as it is fed against the grinding wheel. To grind an internal surface, a small wheel moves inside the hollow of the workpiece, which is gripped in a rotating chuck. On a surface grinder, the workpiece is held in place on a table that moves under the rotating abrasive wheel.

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or drilling machine

Machine tool for producing holes in hard substances. The drill is held in a rotating spindle and is fed into the workpiece, which is usually clamped in a vise supported on a table. The drill may be gripped in a chuck with three jaws that move radially in unison, or it may have a tapered shank that fits into a tapered hole in the spindle. Means are provided for varying the spindle speed and (on some machines) for automatically feeding the drill into the workpiece. Seealso boring machine.

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Machine tool, usually hydraulically operated, for finishing surfaces by drawing or pushing a cutter called a broach entirely over and past the surface. A broach has a series of cutting teeth arranged in a row or rows, graduated in height from the teeth that cut first to those that cut last. Each tooth removes only a few thousandths of an inch, and the total depth of cut is distributed over all the teeth. Broaching is particularly suitable for internal surfaces such as holes and internal gears, but it can also shape external gears and flat surfaces.

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Machine tool for producing smooth and accurate holes in a workpiece by enlarging existing holes with a cutting tool, which may bear a single tip of steel, cemented carbide, or diamond or may be a small grinding wheel. The hole's diameter is controlled by adjusting the boring head. Bored holes are more accurate in roundness, concentricity, and parallelism than drilled holes. Boring machines used in toolmaking shops have a vertical spindle and a work-holding table that moves horizontally in two perpendicular directions so that holes can be accurately spaced. In mass-production plants, boring machines with multiple spindles are common. Seealso drill; drill press; lathe.

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Hypothetical computing device proposed by Alan M. Turing (1936). Not actually a machine, it is an idealized mathematical model that reduces the logical structure of any computing device to its essentials. It consists of an infinitely extensible tape, a tape head that is capable of performing various operations on the tape, and a modifiable control mechanism in the head that can store instructions. As envisaged by Turing, it performs its functions in a sequence of discrete steps. His extrapolation of the essential features of information processing was instrumental in the development of modern digital computers, which share his basic scheme of an input/output device (tape and tape reader), central processing unit (CPU, or control mechanism), and stored memory.

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