1.
Fax
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Fax, sometimes called telecopying or telefax, is the telephonic transmission of scanned printed material, normally to a telephone number connected to a printer or other output device. The receiving fax machine interprets the tones and reconstructs the image, early systems used direct conversions of image darkness to audio tone in a continuous or analog manner. Since the 1980s, most machines modulate the audio frequencies using a digital representation of the page which is compressed to quickly transmit areas which are all-white or all-black. Scottish inventor Alexander Bain worked on chemical mechanical fax type devices and he received British patent 9745 on May 27,1843 for his Electric Printing Telegraph. Frederick Bakewell made several improvements on Bains design and demonstrated a telefax machine, the Pantelegraph was invented by the Italian physicist Giovanni Caselli. He introduced the first commercial service between Paris and Lyon in 1865, some 11 years before the invention of the telephone. In 1880, English inventor Shelford Bidwell constructed the scanning phototelegraph that was the first telefax machine to scan any two-dimensional original, previously, photographs had been sent over the radio using this process. The Western Union Deskfax fax machine, announced in 1948, was a machine that fit comfortably on a desktop. As a designer for the Radio Corporation of America, in 1924, Richard H. Ranger invented the wireless photoradiogram, or transoceanic radio facsimile, the forerunner of today’s fax machines. A photograph of President Calvin Coolidge sent from New York to London on November 29,1924 became the first photo picture reproduced by transoceanic radio facsimile, commercial use of Ranger’s product began two years later. Also in 1924, Herbert E. Ives of AT&T Corporation transmitted and reconstructed the first color facsimile, around 1952 or so, Finch Facsimile, a highly developed machine, was described in detail in a book, it was never manufactured in quantity. By the late 1940s, radiofax receivers were sufficiently miniaturized to be fitted beneath the dashboard of Western Unions Telecar telegram delivery vehicles, in the 1960s, the United States Army transmitted the first photograph via satellite facsimile to Puerto Rico from the Deal Test Site using the Courier satellite. Radio fax is still in limited use today for transmitting weather charts, in 1964, Xerox Corporation introduced what many consider to be the first commercialized version of the modern fax machine, under the name or Long Distance Xerography. This model was superseded two years later with a unit that would set the standard for fax machines for years to come. Up until this point facsimile machines were expensive and hard to operate. In 1966, Xerox released the Magnafax Telecopiers, a smaller and this unit was far easier to operate and could be connected to any standard telephone line. This machine was capable of transmitting a letter-sized document in about six minutes, the first sub-minute, digital fax machine was developed by Dacom, which built on digital data compression technology originally developed at Lockheed for satellite communication. By the late 1970s, many companies around the world, entered the fax market, very shortly after a new wave of more compact, faster and efficient fax machines would hit the market
2.
Potentiometer
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A potentiometer, informally a pot, is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a resistor or rheostat. The measuring instrument called a potentiometer is essentially a voltage divider used for measuring electric potential, potentiometers are commonly used to control electrical devices such as volume controls on audio equipment. Potentiometers operated by a mechanism can be used as transducers, for example. Potentiometers are rarely used to control significant power, since the power dissipated in the potentiometer would be comparable to the power in the controlled load. The resistive element can be flat or angled, each end of the resistive element is connected to a terminal on the case. The wiper is connected to a terminal, usually between the other two. On panel potentiometers, the wiper is usually the terminal of three. For single-turn potentiometers, this wiper typically travels just under one revolution around the contact, the only point of ingress for contamination is the narrow space between the shaft and the housing it rotates in. Another type is the slider potentiometer, which has a wiper which slides along a linear element instead of rotating. Contamination can potentially enter anywhere along the slot the slider moves in, making effective sealing more difficult, an advantage of the slider potentiometer is that the slider position gives a visual indication of its setting. The resistive element of inexpensive potentiometers is often made of graphite, other materials used include resistance wire, carbon particles in plastic, and a ceramic/metal mixture called cermet. Others are enclosed within the equipment and are intended to be adjusted to calibrate equipment during manufacture or repair and they are usually physically much smaller than user-accessible potentiometers, and may need to be operated by a screwdriver rather than having a knob. They are usually called preset potentiometers or trim pots, some presets are accessible by a small screwdriver poked through a hole in the case to allow servicing without dismantling. Multiturn potentiometers are also operated by rotating a shaft, but by several turns rather than less than a full turn, a string potentiometer is a multi-turn potentiometer operated by an attached reel of wire turning against a spring, enabling it to convert linear position to a variable resistance. User-accessible rotary potentiometers can be fitted with a switch which operates usually at the extreme of rotation. Multiple resistance elements can be ganged together with their contacts on the same shaft, for example. The relationship between position and resistance, known as the taper or law, is controlled by the manufacturer
3.
Servomechanism
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In control engineering a servomechanism, sometimes shortened to servo, is an automatic device that uses error-sensing negative feedback to correct the action of a mechanism. It usually includes a built-in encoder or other position feedback mechanism to ensure the output is achieving the desired effect, the term correctly applies only to systems where the feedback or error-correction signals help control mechanical position, speed or other parameters. For example, a power window control is not a servomechanism. By contrast a cars cruise control uses closed-loop feedback, which classifies it as a servomechanism, a common type of servo provides position control. Commonly, servos are electrical, hydraulic or pneumatic and they operate on the principle of negative feedback, where the control input is compared to the actual position of the mechanical system as measured by some sort of transducer at the output. Any difference between the actual and wanted values is amplified and used to drive the system in the necessary to reduce or eliminate the error. This procedure is one widely used application of control theory, typical servos can give a rotary or linear output. Speed control via a governor is another type of servomechanism, the steam engine uses mechanical governors, another early application was to govern the speed of water wheels. Prior to World War II the constant speed propeller was developed to control engine speed for maneuvering aircraft, fuel controls for gas turbine engines employ either hydromechanical or electronic governing. Positioning servomechanisms were first used in military fire-control and marine navigation equipment, other examples are fly-by-wire systems in aircraft which use servos to actuate the aircrafts control surfaces, and radio-controlled models which use RC servos for the same purpose. Many autofocus cameras also use a servomechanism to accurately move the lens, a hard disk drive has a magnetic servo system with sub-micrometre positioning accuracy. In industrial machines, servos are used to perform complex motion, a servomotor is a specific type of motor that is combined with a rotary encoder or a potentiometer to form a servomechanism. This assembly may in turn part of another servomechanism. Potentiometers are subject to drift when the temperature changes whereas encoders are more stable, servomotors are used for both high-end and low-end applications. On the high end are precision industrial components that use a rotary encoder, on the low end are inexpensive radio control servos used in radio-controlled models which use a free-running motor and a simple potentiometer position sensor with an embedded controller. The term servomotor generally refers to an industrial component while the term servo is most often used to describe the inexpensive devices that employ a potentiometer. Stepper motors are not considered to be servomotors, although they too are used to construct larger servomechanisms, stepper motors have inherent angular positioning, owing to their construction, and this is generally used in an open-loop manner without feedback. They are generally used for medium-precision applications, RC servos are used to provide actuation for various mechanical systems such as the steering of a car, the control surfaces on a plane, or the rudder of a boat
4.
Pen
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A pen is a writing implement used to apply ink to a surface, such as paper, for writing or drawing. Historically, reed pens, quill pens, and dip pens were used, ruling pens allow precise adjustment of line width, and still find a few specialized uses, but technical pens such as the Rapidograph are more commonly used. Modern types also include ballpoint, rollerball, fountain, and felt or ceramic tip pens, the ink dries almost immediately on contact with paper. The ballpoint pen is usually reliable and comes in both inexpensive and expensive types and it has replaced the fountain pen as the most common tool for everyday writing. A rollerball pen dispenses a water-based liquid or gel ink through a ball tip similar to that of a ballpoint pen, the less-viscous ink is more easily absorbed by paper than oil-based ink, and the pen moves more easily across a writing surface. The rollerball pen was designed to combine the convenience of a ballpoint pen with the smooth wet ink effect of a fountain pen. A fountain pen uses water-based liquid ink delivered through a nib, the ink flows from a reservoir through a feed to the nib, then through the nib, due to capillary action and gravity. The nib has no moving parts and delivers ink through a slit to the writing surface. A fountain pen reservoir can be refillable or disposable, this type being an ink cartridge. A pen with a refillable reservoir may have a mechanism, such as a piston, to ink from a bottle through the nib. Refill reservoirs, also known as cartridge converters, are available for some pens which use disposable cartridges, a marker, or felt-tip pen, has a porous tip of fibrous material. The smallest, finest-tipped markers are used for writing on paper, medium-tip markers are often used by children for coloring and drawing. Larger markers are used for writing on other such as corrugated boxes, whiteboards and for chalkboards. Markers with wide tips and bright but transparent ink, called highlighters, are used to mark existing text, markers designed for children or for temporary writing typically use non-permanent inks. Large markers used to label shipping cases or other packages are usually permanent markers, a dip pen usually has no ink reservoir and must be repeatedly recharged with ink while drawing or writing. The dip pen has certain advantages over a fountain pen, dip pens are now mainly used in illustration, calligraphy, and comics. The ink brush is the writing implement in East Asian calligraphy. The body of the brush can be made from bamboo, or rarer materials such as red sandalwood, glass, ivory, silver
5.
Elisha Gray
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Elisha Gray was an American electrical engineer who co-founded the Western Electric Manufacturing Company. Gray is best known for his development of a prototype in 1876 in Highland Park. Bells telephone patent was held up in court decisions. Gray is also considered to be the father of the music synthesizer. He was one of the founders of Graybar, purchasing a controlling interest in the shortly after its inception. Born into a Quaker family in Barnesville, Ohio, Gray was brought up on a farm and he spent several years at Oberlin College where he experimented with electrical devices. Although Gray did not graduate, he taught electricity and science there, in 1862 while at Oberlin, Gray met and married Delia Minerva Shepard. In 1865 Gray invented a telegraph relay that automatically adapted to varying insulation of the telegraph line. In 1867 Gray received a patent for the invention, the first of more than seventy, in 1869, Elisha Gray and his partner Enos M. Barton founded Gray & Barton Co. in Cleveland, Ohio to supply telegraph equipment to the giant Western Union Telegraph Company. The electrical distribution business was spun off and organized into a separate company, Graybar Electric Company. Barton was employed by Western Union to examine and test new products, in 1870 financing for Gray & Barton Co. was arranged by General Anson Stager, a superintendent of the Western Union Telegraph Company. Stager became a partner in Gray & Barton Co. The company moved to Chicago near Highland Park, Gray later gave up his administrative position as chief engineer to focus on inventions that could benefit the telegraph industry. Grays inventions and patent costs were financed by a dentist, Dr. Samuel S. White of Philadelphia, in 1870, Gray developed a needle annunciator for hotels and another for elevators. He also developed a microphone printer which had a typewriter keyboard, in 1872 Western Union, then financed by the Vanderbilts and J. P. Morgan, bought one-third of Gray and Barton Co. and changed the name to Western Electric Manufacturing Company of Chicago. Gray continued to invent for Western Electric, in 1874, Gray retired to do independent research and development. Gray applied for a patent on a telegraph which consisted of multi-tone transmitters. Gray gave several demonstrations of this invention in New York and Washington, D. C. in May
6.
World's Columbian Exposition
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The Worlds Columbian Exposition was a worlds fair held in Chicago in 1893 to celebrate the 400th anniversary of Christopher Columbuss arrival in the New World in 1492. The centerpiece of the Fair, the water pool, represented the long voyage Columbus took to the New World. Chicago bested New York City, Washington, D. C. the Exposition was an influential social and cultural event and had a profound effect on architecture, sanitation, the arts, Chicagos self-image, and American industrial optimism. The layout of the Chicago Columbian Exposition was, in part, designed by John Wellborn Root, Daniel Burnham, Frederick Law Olmsted. It was the prototype of what Burnham and his colleagues thought a city should be and it was designed to follow Beaux Arts principles of design, namely French neoclassical architecture principles based on symmetry, balance, and splendor. The color of the generally used to cover the buildings facades gave the fairgrounds its nickname. Many prominent architects designed its 14 great buildings, artists and musicians were featured in exhibits and many also made depictions and works of art inspired by the exposition. The exposition covered more than 600 acres, featuring nearly 200 new buildings of predominantly neoclassical architecture, canals and lagoons, more than 27 million people attended the exposition during its six-month run. Dedication ceremonies for the fair were held on October 21,1892, the fair continued until October 30,1893. On October 9,1893, the day designated as Chicago Day, the debt for the fair was soon paid off with a check for $1.5 million. Chicago has commemorated the fair one of the stars on its municipal flag. Schwab, Chicago railroad and manufacturing magnate John Whitfield Bunn, and Connecticut banking, insurance, the fair was planned in the early 1890s during the Gilded Age of rapid industrial growth, immigration, and class tension. Worlds fairs, such as Londons 1851 Crystal Palace Exhibition, had been successful in Europe as a way to bring together societies fragmented along class lines, the first American attempt at a worlds fair in Philadelphia in 1876, drew crowds but was a financial failure. Nonetheless, ideas about distinguishing the 400th anniversary of Columbus landing started in the late 1880s. Civic leaders in St. Louis, New York City, Washington DC and Chicago expressed an interest in hosting a fair to generate profits, boost real estate values, Congress was called on to decide the location. What finally persuaded Congress was Chicago banker Lyman Gage, who raised several million dollars in a 24-hour period, over. The exposition corporation and national exposition commission settled on Jackson Park, Daniel H. Burnham was selected as director of works, and George R. Davis as director-general. Burnham emphasized architecture and sculpture as central to the fair and assembled the periods top talent to design the buildings, the temporary buildings were designed in an ornate Neoclassical style and painted white, resulting in the fair site being referred to as the “White City”
7.
Chicago
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Chicago, officially the City of Chicago, is the third-most populous city in the United States. With over 2.7 million residents, it is the most populous city in the state of Illinois, and it is the county seat of Cook County. In 2012, Chicago was listed as a global city by the Globalization and World Cities Research Network. Chicago has the third-largest gross metropolitan product in the United States—about $640 billion according to 2015 estimates, the city has one of the worlds largest and most diversified economies with no single industry employing more than 14% of the workforce. In 2016, Chicago hosted over 54 million domestic and international visitors, landmarks in the city include Millennium Park, Navy Pier, the Magnificent Mile, Art Institute of Chicago, Museum Campus, the Willis Tower, Museum of Science and Industry, and Lincoln Park Zoo. Chicagos culture includes the arts, novels, film, theater, especially improvisational comedy. Chicago also has sports teams in each of the major professional leagues. The city has many nicknames, the best-known being the Windy City, the name Chicago is derived from a French rendering of the Native American word shikaakwa, known to botanists as Allium tricoccum, from the Miami-Illinois language. The first known reference to the site of the current city of Chicago as Checagou was by Robert de LaSalle around 1679 in a memoir, henri Joutel, in his journal of 1688, noted that the wild garlic, called chicagoua, grew abundantly in the area. In the mid-18th century, the area was inhabited by a Native American tribe known as the Potawatomi, the first known non-indigenous permanent settler in Chicago was Jean Baptiste Point du Sable. Du Sable was of African and French descent and arrived in the 1780s and he is commonly known as the Founder of Chicago. In 1803, the United States Army built Fort Dearborn, which was destroyed in 1812 in the Battle of Fort Dearborn, the Ottawa, Ojibwe, and Potawatomi tribes had ceded additional land to the United States in the 1816 Treaty of St. Louis. The Potawatomi were forcibly removed from their land after the Treaty of Chicago in 1833, on August 12,1833, the Town of Chicago was organized with a population of about 200. Within seven years it grew to more than 4,000 people, on June 15,1835, the first public land sales began with Edmund Dick Taylor as U. S. The City of Chicago was incorporated on Saturday, March 4,1837, as the site of the Chicago Portage, the city became an important transportation hub between the eastern and western United States. Chicagos first railway, Galena and Chicago Union Railroad, and the Illinois, the canal allowed steamboats and sailing ships on the Great Lakes to connect to the Mississippi River. A flourishing economy brought residents from rural communities and immigrants from abroad, manufacturing and retail and finance sectors became dominant, influencing the American economy. The Chicago Board of Trade listed the first ever standardized exchange traded forward contracts and these issues also helped propel another Illinoisan, Abraham Lincoln, to the national stage
8.
Signalling control
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Currently these decentralised systems are being consolidated into wide scale signalling centres or dispatch offices. Whatever the form, signalling control provides an interface between the signal operator and the lineside signalling equipment. The technical apparatus used to control switches, signals and block systems is called interlocking, originally, all signalling was done by mechanical means. Before long, it was realised that control should be concentrated into one building, the signal box provided a dry, climate controlled space for the complex interlocking mechanics and also the signalman. The raised design of most signal boxes also provided the signalman with a view of the railway under his control. The first use of a box was by the London and Croydon Railway in 1843 to control the junction to Bricklayers Arms in London. Power operated switch points and signalling decides greatly expanded the territory that a control point could operate from several hundred yards to several miles. As the technology of electric relay logic was developed, it no longer necessary for signalmen to operate control devices with any sort of mechanical logic at all. With the jump to all logic, physical presence was no longer needed. Another advancement made possible by the replacement of mechanical control by all systems was that the signalmans user interface could be enhanced to further improve productivity. The smaller size of electric toggles and push buttons put more functionality within reach of an individual signalman, route-setting technology automated the setting of individual points and routes through busy junctions. Computerised video displays removed the physical interface altogether, replacing it with a point-and-click or touchscreen interface, finally, the use of Automatic Route Setting removed the need for any human input at all as common train movements could be fully automated according to a schedule or other scripted logic. Signal boxes also served as important communications hubs, connecting the parts of a rail line. The first signalling systems were possible by technology like the telegraph. Later, the telephone put centralised dispatchers in contact with distant signal boxes, the ultimate ability for data to be transmitted over long distances has proven the demise of most local control signal boxes. Signalmen next to the track are no longer needed to serve as the eyes, track circuits transmit train locations to distant control centres and data links allow direct manipulation of the points and signals. In any node-based control system, proper identification is critical to ensuring that messages are received by their intended recipients. As such, signalling control points are provided with names or identifiers that minimise the likelihood of confusion during communications, popular naming techniques include using nearby geographic references, line milepost numbers, sequence numbers and identification codes
9.
Grand Central Terminal
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Grand Central Terminal is a commuter, rapid transit railroad terminal at 42nd Street and Park Avenue in Midtown Manhattan in New York City, United States. Its platforms, all ground, serve 41 tracks on the upper level and 26 on the lower, though the total number of tracks along platforms. The terminal serves commuters traveling on the Metro-North Railroad to Westchester, Putnam, until 1991, the terminal served Amtrak, which moved to nearby Pennsylvania Station upon completion of the Empire Connection. The East Side Access project is underway to bring Long Island Rail Road service to the terminal, Grand Central Terminal has intricate designs both on its inside and outside. In addition, it contains a vast interior main concourse, the terminal is one of the worlds most visited tourist attractions, with 21.9 million visitors in 2013. Unlike other Metro-North stations, Grand Central Terminal is not owned by the Metropolitan Transportation Authority, Grand Central Station is the name of the nearby U. S. Post Office station at 450 Lexington Avenue, but may refer to the Grand Central – 42nd Street subway station that is located next to the terminal. The tracks are numbered according to their location in the terminal building, the upper-level tracks are numbered 11 to 42 east to west. Tracks 22 and 31 were removed in the late 1990s to build concourses for Grand Central North, Track 12 was removed to expand the platform between tracks 11 and 13 and track 14 is only used for loading a garbage train. The lower level has 27 tracks, numbered 100 to 126, east to west, currently, only tracks 102–112, odd-numbered tracks are usually on the east side of the platform, even-numbered tracks on the west. Grand Central Terminal has both monumental spaces and meticulously crafted detail, especially on its facade, in a February 2013 BBC News article, historian David Cannadine described it as one of the most majestic buildings of the twentieth century. In 2013, Grand Central Terminal hosted 21.6 million visitors, among them are chain stores, including a Starbucks coffee shop, a Rite Aid pharmacy and, as of December 2011, an Apple Store. Other chain restaurants include a Shake Shack, Grand Central Terminals 49-acre basements are among the largest in the city. This includes M42, a secret sub-basement under the terminal that contains the AC to DC converters used to supply DC traction current to the tracks. The exact location of M42 is a guarded secret and does not appear on maps, though it has been shown on the History Channel program Cities of the Underworld. Two of the rotary converters were not removed in the late 20th century when solid-state ones took over their job. During World War II, this facility was closely guarded because its sabotage would have impaired troop movement on the Eastern Seaboard. It is said that any unauthorized person entering the facility during the war risked being shot on sight, abwehr sent two spies to sabotage it, they were arrested by the FBI before they could strike
"Telautograph". The New Student's Reference Work. 1914.
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