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e48219bd41c81b89893452a92be58721 | https://www.britannica.com/technology/Newton-MessagePad | Newton MessagePad | Newton MessagePad
released the Newton MessagePad, for which John Sculley, then Apple’s chief executive officer, coined the term PDA. Although an improvement in some areas, the Newton’s handwriting recognition was only 85 percent effective, resulting in ridicule and poor sales.
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c1dfbd639b127200b1fc0b13d54ccad3 | https://www.britannica.com/technology/noria | Noria | Noria
Noria, undershot waterwheel used to raise water in primitive irrigation systems. It was described by the Roman architect Vitruvius (c. 1st century bce). As the noria turns, pots or hollow chambers on the rim fill when submerged and empty automatically into a trough when they reach or exceed the level of the cent... |
6d86aa8bf383c30d0900a99d9873ef00 | https://www.britannica.com/technology/notebook-computer | Notebook computer | Notebook computer
…to envision developing small “notebook” computers. Kay created a computer programming language for it called Smalltalk. Although the technology was not yet available to produce his “Dynabook,” Smalltalk was instrumental in creating the graphical user interface for the Alto. Smalltalk was the first tr... |
144f0b94e80dac843d7ce2fba1e5d9f6 | https://www.britannica.com/technology/nuclear-reactor/Types-of-reactors | Types of reactors | Types of reactors
Most of the world’s existing reactors are power reactors, providing the heat needed to turn turbines that run electric-power generators. There are also numerous research reactors, and some navies of the world have submarines or surface ships driven by propulsion reactors. There are several types of po... |
f394f3b1bd7d9e7b7655f85cb09c8e17 | https://www.britannica.com/technology/nuclear-weapon | Nuclear weapon | Nuclear weapon
Nuclear weapon, device designed to release energy in an explosive manner as a result of nuclear fission, nuclear fusion, or a combination of the two processes. Fission weapons are commonly referred to as atomic bombs. Fusion weapons are also referred to as thermonuclear bombs or, more commonly, hydrogen... |
cce9256df4001d07e3fa31a73062f969 | https://www.britannica.com/technology/nuclear-weapon/Founding-the-Manhattan-Project | Founding the Manhattan Project | Founding the Manhattan Project
The United States’ entry into World War II in December 1941 was decisive in providing funds for a massive research and production effort for obtaining fissionable materials, and in May 1942 the momentous decision was made to proceed simultaneously on all promising production methods. Vann... |
476b1e61a0082d735691ffba9c057202 | https://www.britannica.com/technology/nuclear-weapon/Pakistan | Pakistan | Pakistan
Pakistan took advantage of the Atoms for Peace program by sending students abroad for training in nuclear technologies and by accepting an American-built research reactor, which began operation in 1965. Although its military nuclear research up to that point had been minimal, the situation soon changed. Pakist... |
f036ccc8e5691a842a50dafcb547b7e2 | https://www.britannica.com/technology/Nyquist-stability-theorem | Nyquist stability theorem | Nyquist stability theorem
His criterion, generally called the Nyquist stability theorem, is of great practical importance. During World War II it helped control artillery employing electromechanical feedback systems.
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84ccb8975abfd619f8a3b8ff98170718 | https://www.britannica.com/technology/object-oriented-database | Object-oriented database | Object-oriented database
Object-oriented databases store and manipulate more complex data structures, called “objects,” which are organized into hierarchical classes that may inherit properties from classes higher in the chain; this database structure is the most flexible and adaptable.
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9e2160b10eb95108fde866456843814b | https://www.britannica.com/technology/ocean-fertilization | Ocean fertilization | Ocean fertilization
Ocean fertilization, untested geoengineering technique designed to increase the uptake of carbon dioxide (CO2) from the air by phytoplankton, microscopic plants that reside at or near the surface of the ocean. The premise is that the phytoplankton, after blooming, would die and sink to the ocean fl... |
e4722d870f9f74915ccb3d86b5555351 | https://www.britannica.com/technology/ocean-thermal-energy-conversion | Ocean thermal energy conversion | Ocean thermal energy conversion
Ocean thermal energy conversion (OTEC), form of energy conversion that makes use of the temperature differential between the warm surface waters of the oceans, heated by solar radiation, and the deeper cold waters to generate power in a conventional heat engine. The difference in temper... |
b9460c4c8420447c372aa761abe375d3 | https://www.britannica.com/technology/oculus | Oculus | Oculus
Oculus, (Latin: “eye”), in architecture, any of several structural elements resembling an eye. A small window that is circular or oval in shape, such as an oeil-de-boeuf window (q.v.), is an oculus. The round opening at the top of some domes, or cupolas, is also an oculus; one example of this kind is found in ... |
2bc37b3d936afc3324c4bee232ce9152 | https://www.britannica.com/technology/offset-printing | Offset printing | Offset printing
Offset printing, also called offset lithography, or litho-offset, in commercial printing, widely used printing technique in which the inked image on a printing plate is printed on a rubber cylinder and then transferred (i.e., offset) to paper or other material. The rubber cylinder gives great flexibili... |
3e844e3a0171b1ebc21ccdaed1a0b881 | https://www.britannica.com/technology/Oldsmobile | Oldsmobile | Oldsmobile
…designer of the three-horsepower, curved-dash Oldsmobile, the first commercially successful American-made automobile and the first to use a progressive assembly system, which foreshadowed modern mass-production methods.
…market with a famous curved-dash Oldsmobile buggy in 1901. Although the first Oldsmobil... |
44b5a3215783c43b3453996b7d136a34 | https://www.britannica.com/technology/onager-weapon | Onager | Onager
Onager, in weaponry, ancient Roman torsion-powered weapon, similar to a catapult. It consisted of a single vertical beam thrust through a thick horizontal skein of twisted cords. The skein was twisted tight by geared winches, and the beam was then pulled down to a horizontal position, further increasing the twi... |
1e9341370c29188cc6ea51079701f1c9 | https://www.britannica.com/technology/one-horse-shay | One-horse shay | One-horse shay
One-horse shay, also called cheer (for chair), or whisky (because its light weight enabled it to whisk about), open two-wheeled vehicle that was the American adaptation of the French chaise. Its chairlike body, seating the passengers on one seat above the axle, was hung by leather braces from a pair of ... |
6b07ea1f1197681f7792819581968509 | https://www.britannica.com/technology/online-gaming | Online gaming | Online gaming
Online gaming, electronic game playing over a computer network, particularly over the Internet.
Electronic game worlds have generated billions of dollars, with millions of players around the world fighting, buying, crafting, and selling in a variety of online environments. One of the most populous was A... |
1f936129a041aaae9385e0da7a30909a | https://www.britannica.com/technology/operating-system | Operating system | Operating system
Operating system (OS), program that manages a computer’s resources, especially the allocation of those resources among other programs. Typical resources include the central processing unit (CPU), computer memory, file storage, input/output (I/O) devices, and network connections. Management tasks inclu... |
7913d66368bc761d13928e788b6e6bb0 | https://www.britannica.com/technology/optical-axis | Optical axis | Optical axis
Optical axis, the straight line passing through the geometrical centre of a lens and joining the two centres of curvature of its surfaces. Sometimes the optical axis of a lens is called its principal axis. The path of a light ray along this axis is perpendicular to the surfaces and, as such, will be unch... |
e21db65beaa540ee8f2a95f76bc3fc9b | https://www.britannica.com/technology/optical-invariant | Optical invariant | Optical invariant
It is frequently as important to determine the size of an image as it is to determine its location. To obtain an expression for the magnification—that is, the ratio of the size of an image to the size of the object—the following process…
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212dc2e9efef19df01f8ef596e7f01fa | https://www.britannica.com/technology/optical-pyrometer | Optical pyrometer | Optical pyrometer
Optical pyrometers, for example, measure the temperature of incandescent bodies by comparing them visually with a calibrated incandescent filament that can be adjusted in temperature. In an elementary radiation pyrometer, the radiation from the hot object is focused onto a thermopile, a collection of ... |
0496585d27882a9649432b8338d1b3c9 | https://www.britannica.com/technology/opus-caementicum | Opus caementicum | Opus caementicum
…form a true concrete, called opus caementicium. This concrete was still used with brick forms in walls, but soon it began to be placed into wooden forms, which were removed after the concrete had hardened.
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c40a71517f11b2a845e2cf29624351bd | https://www.britannica.com/technology/opus-quadratum | Opus quadratum | Opus quadratum
…type of masonry was called opus quadratum.
…examples of what they called opus quadratum, or structures of cut stone blocks laid in regular courses. Most of these were public works in conquered provinces, such as the late 1st-century-bce Pont du Gard, a many-arched bridge and aqueduct spanning 22 metres ... |
67cb453ec3598532f9e24bab0e5d63ba | https://www.britannica.com/technology/Oriental-lacquer | Oriental lacquer | Oriental lacquer
Oriental lacquer, varnish resin derived from a tree indigenous to China, species Rhus vernicifera, commonly known as the varnish tree (q.v.). The manufacturing process was introduced into Japan and remained secret for centuries. A milklike emulsion secured from the tree is concentrated by evaporation... |
f00ebc6b559a65176b1b24c583513367 | https://www.britannica.com/technology/orientation-architecture | Orientation | Orientation
Orientation, (from Latin oriens, orientum, “the rising sun”), in architecture, the position of a building in relation to an east-west axis. In Mesopotamia and Egypt, as well as in pre-Columbian Central America, the important features of the buildings, such as entrances and passages, faced east, in the dir... |
2e357ef740306e5ae419879b8efd76d3 | https://www.britannica.com/technology/orientation-fibre-manufacturing | Orientation | Orientation
The spinning processes described above produce some orientation of the long polymers that form spun filaments. Orientation is completed by stretching, or drawing, the filament, a process that pulls the long polymer chains into alignment along the longitudinal axis of the fibre and causes…
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75ddefd972761e41cb2f709e372db272 | https://www.britannica.com/technology/ornithopter | Ornithopter | Ornithopter
Ornithopter, machine designed to fly by the flapping of its wings in imitation of birds. The wooden bird said to have been made about 400 bc by Archytas of Tarentum is one of the earliest examples. The Greek myth of Daedalus and Icarus involves man’s use of wings in the manner of birds. Leonardo da Vinci m... |
6c6f8da62e4e9809dad941389971683d | https://www.britannica.com/technology/outboard-motorboat | Outboard motorboat | Outboard motorboat
Subsequent outboard motors followed his transmission design, which used a vertical drive shaft with bevel gears (a set of two wheellike gears the teeth of which engage at an angle). In 1910 he founded Evinrude Motors in Milwaukee; renamed Outboard Motor Corporation, the firm was merged…
An outboard m... |
a3cafcc32f131c2883a0fec587f9baf6 | https://www.britannica.com/technology/output-winding | Output winding | Output winding
…both the field and the output winding are on the stator. In the homopolar type of machine, the magnetic flux is produced by direct current in a stationary field coil concentric with the shaft. In the heteropolar type, the field coils are in slots in the stator.
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7941c100b31c17cd96741cfda17d7c6b | https://www.britannica.com/technology/overshot-loader | Overshot loader | Overshot loader
…vein deposits, tracked or rubber-tired overshot loaders are often employed. After the bucket of this machine is filled by being forced into the pile, it is lifted and rotated backward so that it dumps into a built-in dump box or attached railcar. Overshot loaders are commonly powered by compressed air.... |
29d38068ef6ac3017b2b7bfcf73e303b | https://www.britannica.com/technology/oxygenator | Oxygenator | Oxygenator
The oxygenator removes carbon dioxide and adds oxygen to the blood that is pumped into the arterial system. The blood pumped back into the patient’s arteries is sufficient to maintain life at even the most distant parts of the body as well as in those organs…
Blood then flows into an oxygenator, the lung com... |
e91d42b61fb9aa6a0618f4ae813aff52 | https://www.britannica.com/technology/ozone-crack | Ozone crack | Ozone crack
…result, small, deep fissures, termed ozone cracks, are formed if the rubber is stretched slightly (by more than about 10 percent). Cracks one millimetre long appear in unprotected rubber after only a few weeks of exposure to a typical outdoor concentration of ozone, about 5 parts per 100 million. However,…... |
1ef87d4c0dbb9d19b70a338d1bd0b5c8 | https://www.britannica.com/technology/package-ceramics | Package ceramics | Package ceramics
package ceramics, advanced industrial materials that, owing to their insulating qualities, are useful in the production of electronic components.
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2463b9173b67fc153c20b81fe320142b | https://www.britannica.com/technology/pallet-load | Pallet load | Pallet load
…of warehouses, railcars, and trucks, Pallet loads are also called “unit loads” and are the most common way of handling packaged freight. Goods that are not packaged are often handled in bulk. Examples are iron ore, coal, and grains that move in trainload, truckload, and shipload lots. They are loaded,…
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18ae410722ca9a655ce270dbfd443023 | https://www.britannica.com/technology/Palm-Pilot | Palm Pilot | Palm Pilot
, released the first Palm Pilot PDAs, which quickly became the model for other companies to follow. The Pilot did not try to replace the computer but made it possible to organize and carry information with an electronic calendar, a telephone number and address list, a memo pad, and…
, released the Palm Pilot... |
57026578f478066382c0ab706876c45e | https://www.britannica.com/technology/Panzerschreck | Panzerschreck | Panzerschreck
Panzerschreck, shoulder-type rocket launcher used as an antitank weapon by Germany in World War II. The Panzerschreck consisted of a lightweight steel tube about 1.5 metres (5 feet) long that weighed about 9 kg (20 pounds). The tube was open at both ends and was fitted with a hand grip, a trigger mechani... |
640b6c2050adb3fcd78a39172504f01e | https://www.britannica.com/technology/paper-casting-process | Paper-casting process | Paper-casting process
…the waterfall technique and the paper-casting process. In the waterfall technique a conveyor belt carries a flat surface through a continuous, recirculated waterfall of slurry. This method—which is commonly employed to coat candy with chocolate—has also been used to form thin-film dielectrics for... |
3ae394927ba52662e359fc2bec21c849 | https://www.britannica.com/technology/paper-laminate | Paper laminate | Paper laminate
…half-dozen layers of fibrous kraft paper (similar to paper used for grocery bags) together with a surface layer of paper with a printed design—the entire assembly being impregnated with a melamine-formaldehyde resin. For both plywood and the paper laminate, the cross-linking reaction is carried out with... |
b72d2bf4b611a1b9b98bffb83717728b | https://www.britannica.com/technology/paper-pulp | Paper pulp | Paper pulp
Paper pulp, raw material for paper manufacture that contains vegetable, mineral, or man-made fibres. It forms a matted or felted sheet on a screen when moisture is removed.
Rags and other fibres, such as straw, grasses, and bark of the mitsumata and paper mulberry (kozo), have been used as paper pulp. Excep... |
c918a0c73f5dd141e0fd38fb3cffd66d | https://www.britannica.com/technology/papermaking | Papermaking | Papermaking
Papermaking, formation of a matted or felted sheet, usually of cellulose fibres, from water suspension on a wire screen. Paper is the basic material used for written communication and the dissemination of information. In addition, paper and paperboard provide materials for hundreds of other uses, such as w... |
5b4a3859609f32d25d8d122c39bed6f9 | https://www.britannica.com/technology/parachute | Parachute | Parachute
Parachute, device that slows the vertical descent of a body falling through the atmosphere or the velocity of a body moving horizontally. The parachute increases the body’s surface area, and this increased air resistance slows the body in motion. Parachutes have found wide employment in war and peace for sa... |
85b35f29b30a0701b63b1cefcda61644 | https://www.britannica.com/technology/parallel-motion | Parallel motion | Parallel motion
…with his invention of the parallel motion—an arrangement of connected rods that guided the piston rod in a perpendicular motion—which he described as “one of the most ingenious, simple pieces of mechanism I have contrived.” Four years later his application of the centrifugal governor for automatic cont... |
13cb1bc06355828f32077c6f8d137e83 | https://www.britannica.com/technology/Parkesine | Parkesine | Parkesine
…plastic material that he called Parkesine. Parkesine plastics were made by dissolving nitrocellulose (a flammable nitric ester of cotton or wood cellulose) in solvents such as alcohol or wood naphtha and mixing in plasticizers such as vegetable oil or camphor (a waxy substance originally derived from the oil... |
fde1d04981fb81a08fe58048cf409898 | https://www.britannica.com/technology/particle-accelerator/Synchrotrons | Synchrotrons | Synchrotrons
As the particles in a synchrotron are accelerated, the strength of the magnetic field is increased to keep the radius of the orbit approximately constant. This technique has the advantage that the magnet required for forming the particle orbits is much smaller than that needed in a cyclotron to produce the... |
b587214c75234cbaba7650cc0f42c0f1 | https://www.britannica.com/technology/Pascal-computer-language | Pascal | Pascal
Pascal, a computer programming language developed about 1970 by Niklaus Wirth of Switzerland to teach structured programming, which emphasizes the orderly use of conditional and loop control structures without GOTO statements. Although Pascal resembled ALGOL in notation, it provided the ability to define data t... |
2f6ac7be0ac525a7d027550aa933922c | https://www.britannica.com/technology/Pascaline | Pascaline | Pascaline
Pascaline, also called Arithmetic Machine, the first calculator or adding machine to be produced in any quantity and actually used. The Pascaline was designed and built by the French mathematician-philosopher Blaise Pascal between 1642 and 1644. It could only do addition and subtraction, with numbers being e... |
4abadbb3f420b3b940b8d2529805e0fc | https://www.britannica.com/technology/patent-leather | Patent leather | Patent leather
Patent leather, usually made from cattle hide, is given a hard, glossy surface finish. Suede is made from any of several leathers (calf, kid, or cattle hide) by buffing the inner surface to produce a napped finish.
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bae711c0b0aaf569d611de1e9fbff940 | https://www.britannica.com/technology/PDA | PDA | PDA
PDA, in full personal digital assistant, a handheld organizer used to store contact information, manage calendars, communicate by e-mail, and handle documents and spreadsheets, usually in communication with the user’s personal computer.
The first PDAs were developed in the early 1990s as digital improvements upon ... |
a30d4943449e4ad51dbe45087ac39637 | https://www.britannica.com/technology/pebble-chopper | Pebble chopper | Pebble chopper
Pebble chopper, also called pebble tool, primordial cutting tool, the oldest type of tool made by forerunners of modern humans. The tool consists of a rounded stone struck a number of blows with a similar stone used as a pounder, which created a serrated crest that served as a chopping blade. The tool c... |
82f065a2a58a19599a694e1f3267d8b7 | https://www.britannica.com/technology/pen-writing-implement | Pen | Pen
Pen, tool for writing or drawing with a coloured fluid such as ink.
The earliest ancestor of the pen probably was the brush the Chinese used for writing by the 1st millennium bce. The early Egyptians employed thick reeds for penlike implements about 300 bce. A specific allusion to the quill pen occurs in the 7th-c... |
7577245a425f63eb12e98ee70622984e | https://www.britannica.com/technology/periscope | Periscope | Periscope
Periscope, optical instrument used in land and sea warfare, submarine navigation, and elsewhere to enable an observer to see his surroundings while remaining under cover, behind armour, or submerged.
A periscope includes two mirrors or reflecting prisms to change the direction of the light coming from the s... |
80d857072ce3b15b56de8b024e316c73 | https://www.britannica.com/technology/Perl | Perl | Perl
Perl, a cross-platform, open-source computer programming language used widely in the commercial and private computing sectors. Perl is a favourite among Web developers for its flexible, continually evolving text-processing and problem-solving capabilities.
In December 1987 American programmer and linguist Larry W... |
fb330d68a5fe8804295a2acfd9d31479 | https://www.britannica.com/technology/personal-computer/Faster-smaller-and-more-powerful-PCs | Faster, smaller, and more-powerful PCs | Faster, smaller, and more-powerful PCs
These advances in software and operating systems were matched by the development of microprocessors containing ever-greater numbers of circuits, with resulting increases in the processing speed and power of personal computers. The Intel 80386 32-bit microprocessor (introduced 1985... |
f019ef2084d94c16c4b3e77674fc9067 | https://www.britannica.com/technology/petroleum-refinery | Petroleum refinery | Petroleum refinery
Each petroleum refinery is uniquely configured to process a specific raw material into a desired slate of products. In order to determine which configuration is most economical, engineers and planners survey the local market for petroleum products and assess the available raw materials. Since about h... |
a68cd3faa73efee256e4d28fb35fe505 | https://www.britannica.com/technology/phaeton-carriage | Phaeton | Phaeton
Phaeton, open, four-wheeled, doorless carriage, popular in the 18th and 19th centuries. It contained one or two seats, usually had a folding, or falling, top, and was owner-driven (i.e., it had no outside driver’s seat). The most spectacular phaeton was the English four-wheeled high-flyer, the body of which c... |
4778f614cf3e632887d5bb5f9e4a2d40 | https://www.britannica.com/technology/pharmaceutical-industry/Drug-interactions | Drug interactions | Drug interactions
Drug interactions occur when one drug alters the pharmacological effect of another drug. The pharmacological effect of one or both drugs may be increased or decreased, or a new and unanticipated adverse effect may be produced. Drug interactions may result from pharmacokinetic interactions (absorption,... |
5afc8cbcd7749c400ed16ada904ddc19 | https://www.britannica.com/technology/photocomposition | Photocomposition | Photocomposition
Photocomposition, also called Phototypesetting, or Filmsetting, method of assembling or setting type by photographing characters on film from which printing plates are made. The characters are developed as photographic positives on film or light-sensitive paper from a negative master containing all th... |
09145e31b47ccbd3664c488bbf5f7d86 | https://www.britannica.com/technology/photoengraving | Photoengraving | Photoengraving
Photoengraving, any of several processes for producing printing plates by photographic means. In general, a plate coated with a photosensitive substance is exposed to an image, usually on film; the plate is then treated in various ways, depending upon whether it is to be used in a relief (letterpress) o... |
7afda6804cd42b2f439c22b2d58e41b7 | https://www.britannica.com/technology/photoengraving/Production-specifications | Production specifications | Production specifications
These include specifications for line plates, halftone specifications, and combination plates.
In line illustrations all of the image areas are either black or white, and hence no halftone screen is required to copy them for use in making a printing plate. Suitable copy consists of line drawin... |
deb229d9d635fa68ac34102516457f22 | https://www.britannica.com/technology/photography/Photographys-early-evolution-c-1840-c-1900 | Photography’s early evolution, c. 1840–c. 1900 | Photography’s early evolution, c. 1840–c. 1900
Daguerre’s process rapidly spread throughout the world. Before the end of 1839, travelers were buying daguerreotypes of famous monuments in Egypt, Israel, Greece, and Spain; engravings of these works were made and then published in two volumes as Excursions daguerriennes b... |
212a8a6d8463722e45e96c86ba9818d7 | https://www.britannica.com/technology/physical-symbol-system-hypothesis | Physical symbol system hypothesis | Physical symbol system hypothesis
…in what they called the physical symbol system hypothesis. This hypothesis states that processing structures of symbols is sufficient, in principle, to produce artificial intelligence in a digital computer and that, moreover, human intelligence is the result of the same type of symbol... |
1c35c85bbf7f5b8f8d16284087b4f557 | https://www.britannica.com/technology/pile-textiles | Pile | Pile
Pile, in textiles, the surface of a cloth composed of an infinite number of loops of warp threads, or else of an infinite number of free ends of either warp or of weft, or filling, threads that stand erect from the foundation or ground structure of the cloth. In looped pile the loops are uncut; in cut pile the s... |
7c85d17d253687a0904af1c819184573 | https://www.britannica.com/technology/pin-fastener | Pin fastener | Pin fastener
Pin fastener, a steel pin, usually cylindrical, that can keep machine parts in proper alignment or fasten them together. The illustration shows several types of pin fasteners in common use.
Hardened and precisely shaped dowel pins are used to keep machine components in accurate alignment; they are also u... |
b3bc77eb672d6f7f8e04ac29ff5c4718 | https://www.britannica.com/technology/Pioneer-space-probes | Pioneer | Pioneer
Pioneer, any of the first series of unmanned U.S. space probes designed chiefly for interplanetary study. Whereas the first five Pioneers (0–4, launched from 1958 to 1959) were intended to explore the vicinity of the Moon, all other probes in the series were sent to investigate planetary bodies or to measure v... |
b052205f1b47476f6d948bbe586afaff | https://www.britannica.com/technology/pirogue | Pirogue | Pirogue
Pirogue, Spanish Piragua, in its simplest form, a dugout made from one log, but also a number of more elaborately fashioned boats, including various native canoes, the structure and appearance of which generally resemble those of a dugout. The pirogue is widely distributed and may be found as a fishing vessel ... |
7527fb6d9c57120621a1406dd369c0d5 | https://www.britannica.com/technology/pitha | Pīṭhā | Pīṭhā
Pīṭhā, “seats,” or “benches,” of the Goddess, usually numbered at 108 and associated with the parts of the deity’s body and with the various aspects of her divine female power, or śakti. Many of the 108 pīṭhās have become important pilgrimage sites for members of the Shakti sects of Hinduism.
The origin myth for... |
3f2cd3ab1f8ef86873f29093654ad9ea | https://www.britannica.com/technology/pitot-tube | Pitot tube | Pitot tube
Pitot tube, instrument for measuring the velocity (speed) of a flowing fluid. Invented by Henri Pitot (1695–1771), it consists of a tube with a short right-angled bend, which is placed vertically in a moving fluid with the mouth of the bent part directed upstream; the pressure, measured with an attached dev... |
c11f6a509436c91216aed1f34969661c | https://www.britannica.com/technology/plain-stitch | Plain stitch | Plain stitch
Plain stitch, also called Jersey Stitch, Flat Stitch, or Stockinette Stitch, basic knitting stitch in which each loop is drawn through other loops to the right side of the fabric. The loops form vertical rows, or wales, on the fabric face, giving it a sheen, and crosswise rows, or courses, on the back.
Pl... |
e4037ccae242a194e753fb9463a05e0c | https://www.britannica.com/technology/plane-diffraction-grating | Plane diffraction grating | Plane diffraction grating
…gratings are further classified as plane or concave, the latter being a spherical surface ruled with lines that are the projection of equidistant and parallel lines on an imaginary plane surface. The advantage of a concave grating over a plane grating is its ability to produce sharp spectral ... |
b89787470158ae1f1d073d7a51acb670 | https://www.britannica.com/technology/planetary-gear | Planetary gear | Planetary gear
Compound planetary gear trains with multiple sun gears and planet pinions have been designed to provide a low forward speed, intermediate speeds, a reverse, and a means of locking into direct drive. This unit is used with various modifications in almost all hydraulic torque-converter transmissions. All…
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c3ca0a8e51db8f5928dc4bbfa58a9e36 | https://www.britannica.com/technology/plating | Plating | Plating
Plating, coating a metal or other material such as plastic or china with a hard, nonporous metallic surface to improve durability and beauty. Such surfaces as gold, silver, stainless steel, palladium, copper, and nickel are formed by dipping an object into a solution containing the desired surface material, w... |
8764ede5d76f52deeb1005c5e3ff757d | https://www.britannica.com/technology/pliers | Pliers | Pliers
Pliers, hand-operated tool for holding and gripping small articles or for bending and cutting wire. Slip-joint pliers have grooved jaws, and the pivot hole in one member is elongated so that the member can pivot in either of two positions in order to grasp objects of different size in the most effective way. O... |
269e631d2029dbb289ce083bc628e16e | https://www.britannica.com/technology/plinth | Plinth | Plinth
Plinth, Lowest part, or foot, of a pedestal, podium, or architrave (molding around a door). It can also refer to the bottom support of a piece of furniture or the usually projecting stone coursing that forms a platform for a building. Tall stone plinths are often used to add monumentality to temple settings and... |
3bb118873e936398730fd6fae867b582 | https://www.britannica.com/technology/Polybius-checkerboard | Polybius checkerboard | Polybius checkerboard
…by a device called the Polybius checkerboard, which is a true biliteral substitution and presages many elements of later cryptographic systems. Similar examples of primitive substitution or transposition ciphers abound in the history of other civilizations. The Romans used monoalphabetic substitu... |
c6a274257c779958f74d1f977ce44665 | https://www.britannica.com/technology/poppet-valve | Poppet valve | Poppet valve
On gasoline engines, poppet valves are used to control the admission and rejection of the intake and exhaust gases to the cylinders. In the Figure (right centre), the valve, which consists of a disk with a tapered edge attached to a shank, is held against the tapered seat…
…all the so-called poppet, or mus... |
c857814b825ea7585c866464f1b5e978 | https://www.britannica.com/technology/pot-helm | Pot helm | Pot helm
… with nasal evolved into the pot helm, or casque. This was an involved process, with the crown of the helmet losing its pointed shape to become flat and the nasal expanding to cover the entire face except for small vision slits and breathing holes. The late 12th-century helm was typically…
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c1e95070a05334cf3a4ad2c16491f1e6 | https://www.britannica.com/technology/poultry-processing/Defeathering | Defeathering | Defeathering
The carcasses then go through the feather-picking machines, which are equipped with rubber “fingers” specifically designed to beat off the feathers. The carcasses are moved through a sequence of machines, each optimized for removing different sets of feathers. At this point the carcasses are usually singed... |
fa13486ca418a53c3da5e13aff31513b | https://www.britannica.com/technology/power-architecture | Power architecture | Power architecture
As wealth and expressive functions increase, a special type of domestic building can be distinguished that may be called power architecture. In almost every civilization the pattern of society gives to a few of its members the power to utilize the resources of…
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f65c07ad42de9d3710ba3499e8770c20 | https://www.britannica.com/technology/power-shovel | Power shovel | Power shovel
Power shovel, digging and loading machine consisting of a revolving deck with a power plant, driving and controlling mechanisms, sometimes a counterweight, and a front attachment, such as a boom or crane, supporting a handle with a digger at the end. The whole mechanism is mounted on a base platform with... |
f13b2a7828b6282c07d9f8ae95b4bac8 | https://www.britannica.com/technology/Pratt-truss-bridge | Pratt truss bridge | Pratt truss bridge
…most commonly used are the Pratt and the Warren; in the former the sloping web members are parallel to each other, while in the latter they alternate in direction of slope.
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98380f8cfe90693334a3344c51bdf3c5 | https://www.britannica.com/technology/prau | Prau | Prau
Prau, fast, sharp-ended rowing or sailing boat that is widely used in Malayan waters and was once popular with Malayan pirates. The prau is long and narrow, rigged with one or two fore-and-aft sails. Modern praus are generally open and relatively small. In earlier times the boats were decked and measured as much... |
5db167da71aa13d505f6e0fe204f8532 | https://www.britannica.com/technology/Praxinoscope | Praxinoscope | Praxinoscope
…onto a screen using his Praxinoscope, in which revolving mirrors and an oil-lamp “magic lantern” were applied to a zoetrope-like drum, and by 1880 Muybridge was similarly projecting enlarged, illuminated views of his motion photographs using the Zoöpraxiscope, an adaptation of the zoetrope.
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20b093eba969d74f2b0a1b1daa0088dc | https://www.britannica.com/technology/precision-approach-path-indicator | Precision approach path indicator | Precision approach path indicator
… (VASIS) and the more modern precision approach path indicator (PAPI). Both work on the principle of guiding lights that show white when the pilot is above the proper glide slope and red when below.
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9c11adb944b5bf76551543e2b86444cd | https://www.britannica.com/technology/presentation-level | Presentation level | Presentation level
The presentation layer is concerned with functions that encode data, so that heterogeneous systems may engage in meaningful communication. At the highest level are protocols that support specific applications. An example of such an application is the file transfer protocol (FTP), which governs the tr... |
ccfc6e837d883e496742eb8244e0aedb | https://www.britannica.com/technology/pressure-sensitive-adhesive | Pressure-sensitive adhesive | Pressure-sensitive adhesive
Pressure-sensitive adhesives, or PSAs, represent a large industrial and commercial market in the form of adhesive tapes and films directed toward packaging, mounting and fastening, masking, and electrical and surgical applications. PSAs are capable of holding adherends together when the surf... |
25939833fde9525ff825232da23ab5af | https://www.britannica.com/technology/primary-recovery | Primary recovery | Primary recovery
Petroleum reservoirs usually start with a formation pressure high enough to force crude oil into the well and sometimes to the surface through the tubing. However, since production is invariably accompanied by a decline in reservoir pressure, “primary…
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9c0bc20c826cd37a55e655b994d3c892 | https://www.britannica.com/technology/privateer | Privateer | Privateer
Privateer, privately owned armed vessel commissioned by a belligerent state to attack enemy ships, usually vessels of commerce. Privateering was carried on by all nations from the earliest times until the 19th century. Crews were not paid by the commissioning government but were entitled to cruise for their ... |
ea7a559c0586f218251056cbd0c4c5e2 | https://www.britannica.com/technology/production-reactor | Production reactor | Production reactor
The very first nuclear reactors were built for the express purpose of manufacturing plutonium for nuclear weapons, and the euphemism of calling them production reactors has persisted to this day. At present, most of the material produced by such systems is tritium
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e4d81385763477df10591e0b0924dbbd | https://www.britannica.com/technology/propulsor | Propulsor | Propulsor
The gas horsepower generated by the prime mover in the form of hot, high-pressure gas is used to drive the propulsor, enabling it to generate thrust for propelling or lifting the aircraft. The principle on which such a thrust is produced is based on…
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074fb662fbff850d298c51343bb3b1c5 | https://www.britannica.com/technology/prytaneum | Prytaneum | Prytaneum
Prytaneum, Greek Prytaneion, town hall of a Greek city-state, normally housing the chief magistrate and the common altar or hearth of the community. Ambassadors, distinguished foreigners, and citizens who had done signal service were entertained there. Prytanea are attested at Sigeum in the Troas from the 6t... |
f3374497ae3e5571e7514761de797f1e | https://www.britannica.com/technology/psychrometer | Psychrometer | Psychrometer
Psychrometer, a hygrometer composed of two similar thermometers. The bulb of one thermometer is kept wet (by means of a thin, wet cloth wick) so that the cooling that results from evaporation makes it register a lower temperature than the dry-bulb thermometer. When readings are taken simultaneously, it i... |
cc9e980a0c3e51dd1f9929d8f44785a7 | https://www.britannica.com/technology/puddling-process | Puddling process | Puddling process
Puddling process, Method of converting pig iron into wrought iron by subjecting it to heat and frequent stirring in a furnace in the presence of oxidizing substances (see oxidation-reduction). Invented by Henry Cort in 1784 (superseding the finery process), it was the first method that allowed wrought... |
559404b723cadd721b5f1348b3b83acc | https://www.britannica.com/technology/pueblo-architecture | Pueblo architecture | Pueblo architecture
Pueblo architecture, traditional architecture of the Pueblo Indians of the southwestern United States. The multistoried, permanent, attached homes typical of this tradition are modeled after the cliff dwellings built by the Ancestral Pueblo (Anasazi) culture beginning in approximately ad 1150. This... |
dbd9a290ba7877a3959b68fcdae99f0b | https://www.britannica.com/technology/pulse-generator | Pulse generator | Pulse generator
…output frequencies over wide ranges; pulse generators, which produce pulsed signals at precise duration at precise frequencies; and random-noise generators, which produce a wideband noise for various types of electronic, mechanical, and psychological testing.
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e4186be628d119790002b19afa9a18fb | https://www.britannica.com/technology/PUMA-560 | PUMA 560 | PUMA 560
The first surgical robot, PUMA 560, was used in 1985 in a stereotaxic operation, in which computed tomography was used to guide the robot as it inserted a needle into the brain for biopsy, a procedure previously subject to error from hand tremors during needle placement. In 1988 PROBOT,…
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6e480d7ab1f8245d375c491337d54edc | https://www.britannica.com/technology/PUMA-robot | PUMA | PUMA
Called PUMA (Programmable Universal Machine for Assembly), they have been used since 1978 to assemble automobile subcomponents such as dash panels and lights. PUMA was widely imitated, and its descendants, large and small, are still used for light assembly in electronics and other industries. Since the…
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355eebd2f56704b7f93ad0e430798e85 | https://www.britannica.com/technology/pump/Positive-displacement-pumps | Positive displacement pumps. | Positive displacement pumps.
Positive displacement pumps, which lift a given volume for each cycle of operation, can be divided into two main classes, reciprocating and rotary. Reciprocating pumps include piston, plunger, and diaphragm types; rotary pumps include gear, lobe, screw, vane, and cam pumps.
The plunger pump... |
75a0d9fd1cd41c7fbf8af30c5816e716 | https://www.britannica.com/technology/pyramid-architecture | Pyramid | Pyramid
Pyramid, in architecture, a monumental structure constructed of or faced with stone or brick and having a rectangular base and four sloping triangular (or sometimes trapezoidal) sides meeting at an apex (or truncated to form a platform). Pyramids have been built at various times in Egypt, Sudan, Ethiopia, west... |
5050a03ad8b6d8267c85d6ecfa4a44b8 | https://www.britannica.com/technology/QSL-process | QSL process | QSL process
…lead sulfide concentrate are the QSL (Queneau-Schuhmann-Lurgi) and the KIVCET (a Russian acronym for “flash-cyclone-oxygen-electric smelting”). In the QSL reactor a submerged injection of shielded oxygen oxidizes lead sulfide to lead metal, while the KIVCET is a type of flash-smelting furnace in which fine... |
2cec09b1ce8795f2b9df011910034866 | https://www.britannica.com/technology/quinacridone | Quinacridone | Quinacridone
A second group of pigments developed in the 20th century were the quinacridone compounds. Quinacridone itself was introduced in 1958. Its seven crystalline forms range in colour from yellowish-red to violet; the violet β and red γ forms are used as pigments, both…
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