title: Phonograph content: in the wax which had been applied to the Edison phonograph. The following was the text of one of their recordings: "There are more things in heaven and earth, Horatio, than are dreamed of in your philosophy. I am a Graphophone and my mother was a phonograph." Most of the disc machines designed at the Volta Lab had their disc mounted on vertical turntables. The explanation is that in the early experiments, the turntable, with disc, was mounted on the shop lathe, along with the recording and reproducing heads. Later, when the complete models were built, most of them featured


title: Phonograph content: vertical turntables. One interesting exception was a horizontal seven inch turntable. The machine, although made in 1886, was a duplicate of one made earlier but taken to Europe by Chichester Bell. Tainter was granted on July 10, 1888. The playing arm is rigid, except for a pivoted vertical motion of 90 degrees to allow removal of the record or a return to starting position. While recording or playing, the record not only rotated, but moved laterally under the stylus, which thus described a spiral, recording 150 grooves to the inch. The preserved Bell and Tainter records are of both the


title: Phonograph content: lateral cut and the Edison-style "hill-and-dale" (up-and-down) styles. Edison for many years used the "hill-and-dale" method on both his cylinders and Diamond Disc records, and Emile Berliner is credited with the invention of the lateral cut, acid-etched Gramophone record in 1887. The Volta associates, however, had been experimenting with both formats and directions of groove modulation as early as 1881. The basic distinction between the Edison's first phonograph patent and the Bell and Tainter patent of 1886 was the method of recording. Edison's method was to indent the sound waves on a piece of tin foil, while Bell and Tainter's


title: Phonograph content: invention called for cutting, or "engraving", the sound waves into a wax record with a sharp recording stylus. In 1885, when the Volta Associates were sure that they had a number of practical inventions, they filed patent applications and began to seek out investors. The Volta Graphophone Company of Alexandria, Virginia, was created on January 6, 1886 and incorporated on February 3, 1886. It was formed to control the patents and to handle the commercial development of their sound recording and reproduction inventions, one of which became the first Dictaphone. After the Volta Associates gave several demonstrations in the City


title: Phonograph content: of Washington, businessmen from Philadelphia created the American Graphophone Company on March 28, 1887, in order to produce and sell the machines for the budding phonograph marketplace. The Volta Graphophone Company then merged with American Graphophone, which itself later evolved into Columbia Records. Shortly after American Graphophone's creation, Jesse H. Lippincott used nearly $1 million of an inheritance to gain control of it, as well as the rights to the Graphophone and the Bell and Tainter patents. Not long later Lippincott purchased the Edison Speaking Phonograph Company. He then created the North American Phonograph Company to consolidate the national sales


title: Phonograph content: rights of both the Graphophone and the Edison Speaking Phonograph. In the early 1890s Lippincott fell victim to the unit's mechanical problems and also to resistance from stenographers. A coin-operated version of the Graphophone, , was developed by Tainter in 1893 to compete with "nickel-in-the-slot" entertainment phonograph demonstrated in 1889 by Louis T. Glass, manager of the Pacific Phonograph Company. The work of the Volta Associates laid the foundation for the successful use of dictating machines in business, because their wax recording process was practical and their machines were durable. But it would take several more years and the renewed


title: Phonograph content: efforts of Edison and the further improvements of Emile Berliner and many others, before the recording industry became a major factor in home entertainment. Discs are not inherently better than cylinders at providing audio fidelity. Rather, the advantages of the format are seen in the manufacturing process: discs can be stamped; cylinders could not be until 1901–1902 when the gold moulding process was introduced by Edison. Recordings made on a cylinder remain at a constant linear velocity for the entirety of the recording, while those made on a disc have a higher linear velocity at the outer portion of the


title: Phonograph content: groove compared to the inner portion. Edison's patented recording method recorded with vertical modulations in a groove. Berliner utilized a laterally modulated groove. Though Edison's recording technology was better than Berliner's, there were commercial advantages to a disc system since the disc could be easily mass-produced by molding and stamping and it required less storage space for a collection of recordings. Berliner successfully argued that his technology was different enough from Edison's that he did not need to pay royalties on it, which reduced his business expenses. Through experimentation, in 1892 Berliner began commercial production of his disc records, and


title: Phonograph content: "gramophones" or "talking-machines". His "gramophone record" was the first disc record to be offered to the public. They were five inches (12.7 cm) in diameter and recorded on one side only. Seven-inch (17.5 cm) records followed in 1895. Also in 1895 Berliner replaced the hard rubber used to make the discs with a shellac compound. Berliner's early records had poor sound quality, however. Work by Eldridge R. Johnson improved the sound fidelity to a point where it was as good as the cylinder. By 1901, ten-inch (25 cm) records were marketed by Johnson and Berliner's Victor Talking Machine Company, and


title: Phonograph content: Berliner had sold his interests. By 1908, a majority of the public demanded double-sided disc recordings, and cylinders fell into disfavor. Edison felt the commercial pressure for disc records, and by 1912, though reluctant at first, his movement to disc records was in full swing. This was the Edison Disc Record. From the mid-1890s until the early 1920s both phonograph cylinder and disc recordings and machines to play them on were widely mass-marketed and sold. The disc system gradually became more popular because of its cheaper price and better marketing by disc record companies. Edison ceased cylinder manufacture in the


title: Phonograph content: autumn of 1929, and the history of disc and cylinder rivalry was concluded. Berliner's lateral disc record was the ancestor of the 78 rpm, 45 rpm, 33⅓ rpm, and all other analogue disc records popular for use in sound recording through the 20th century. See gramophone record. The 1920s brought improved radio technology and radio sales, bringing many phonograph dealers to near financial ruin. With efforts at improved audio fidelity, the big record companies succeeded in keeping business booming through the end of the decade, but the record sales plummeted during the Great Depression, with many companies merging or going


title: Phonograph content: out of business. Record sales picked up appreciably by the late 30s and early 40s, with greater improvements in fidelity and more money to be spent. By this time home phonographs had become much more common, though it wasn't until the 1940s that console radio/phono set-ups with automatic record changers became more common. In the 1930s, vinyl (originally known as vinylite) was introduced as a record material for radio transcription discs, and for radio commercials. At that time, virtually no discs for home use were made from this material. Vinyl was used for the popular 78-rpm V-discs issued to US


title: Phonograph content: soldiers during World War II. This significantly reduced breakage during transport. The first commercial vinylite record was the set of five 12" discs "Prince Igor" (Asch Records album S-800, dubbed from Soviet masters in 1945). Victor began selling some home-use vinyl 78s in late 1945; but most 78s were made of a shellac compound until the 78-rpm format was completely phased out. (Shellac records were heavier and more brittle.) 33s and 45s were, however, made exclusively of vinyl, with the exception of some 45s manufactured out of polystyrene. Booms in record sales returned after the Second World War, as industry


title: Phonograph content: standards changed from 78s to vinyl, long-playing records (commonly called record albums), which could contain an entire symphony, and 45s which usually contained one hit song popularized on the radio – thus the term "single" record – plus another song on the back or "flip" side. An "extended play" version of the 45 was also available, designated 45 EP, which provided capacity for longer musical selections, or for two regular-length songs per side. In 1955, Philco developed and produced the world's first all-transistor phonograph models TPA-1 and TPA-2, which were announced in the June 28, 1955 edition of the "Wall


title: Phonograph content: Street Journal". Philco started to sell these all-transistor phonographs in the fall of 1955, for the price of $59.95. The October 1955 issue of "Radio & Television News" magazine (page 41), had a full page detailed article on Philco's new consumer product. The all-transistor portable phonograph TPA-1 and TPA-2 models played only 45rpm records and used four 1.5 volt "D" batteries for their power supply. The "TPA" stands for "Transistor Phonograph Amplifier". Their circuitry used three Philco germanium PNP alloy-fused junction audio frequency transistors. After the 1956 season had ended, Philco decided to discontinue both models, for transistors were too


title: Phonograph content: expensive compared to vacuum tubes, but by 1961 a $49.95 ($ in ) portable, battery-powered radio-phonograph with seven transistors was available. By the 1960s, cheaper portable record players and record changers which played stacks of records in wooden console cabinets were popular, usually with heavy and crude tonearms in the portables. The consoles were often equipped with better quality pick-ups. Even pharmacies stocked 45 rpm records at their front counters. Rock music played on 45s became the soundtrack to the 1960s as people bought the same songs that were played free of charge on the radio. Some record players were


title: Phonograph content: even tried in automobiles, but were quickly displaced by 8-track and cassette tapes. High fidelity made great advances during the 1970s, as turntables became very precise instruments with belt or direct drive, jewel-balanced tonearms, some with electronically controlled linear tracking and magnetic cartridges. Some cartridges had frequency response above 30 kHz for use with CD-4 quadraphonic 4 channel sound. A high fidelity component system which cost under $1,000 could do a very good job of reproducing very accurate frequency response across the human audible spectrum from 20 Hz to 20,000 Hz with a $200 turntable which would typically have less


title: Phonograph content: than 0.05% wow and flutter and very low rumble (low frequency noise). A well-maintained record would have very little surface noise, though it was difficult to keep records completely free from scratches, which produced popping noises. Another characteristic failure mode was skipping, or groove lock, causing a section of music to repeat, separated by a popping noise. This was so common that a saying was coined: "you sound like a broken record", referring to someone who is being annoyingly repetitious. A novelty variation on the standard format was the use of multiple concentric spirals with different recordings. Thus when the


title: Phonograph content: record was played multiple times, different recordings would play, seemingly at random. Records themselves became an art form because of the large surface onto which graphics and books could be printed, and records could be molded into unusual shapes, colors, or with images (picture discs). The turntable remained a common element of home audio systems well after the introduction of other media, such as audio tape and even the early years of the compact disc as a lower-priced music format. However, even though the cost of producing CDs fell below that of records, CDs remained a higher-priced music format than


title: Phonograph content: either cassettes or records. Thus, records were not uncommon in home audio systems into the early 1990s. By the turn of the 21st century, the turntable had become a niche product, as the price of CD players, which reproduce music free of pops and scratches, fell far lower than high-fidelity tape players or turntables. Nevertheless, there is some increase in interest; many big-box media stores carry turntables, as do professional DJ equipment stores. Most low-end and mid-range amplifiers omit the phono input; but on the other hand, low-end turntables with built-in phono pre-amplifiers are widely available. Some combination systems include


title: Phonograph content: a basic turntable, a CD player, a cassette deck. and a radio, in a retro-styled cabinet. Records also continue to be manufactured and sold today, albeit in smaller quantities than in the disc phonograph's heyday. Inexpensive record players typically used a flanged steel stamping for the turntable structure. A rubber disc would be secured to the top of the stamping to provide traction for the record, as well as a small amount of vibration isolation. The spindle bearing usually consisted of a bronze bushing. The flange on the stamping provided a convenient place to drive the turntable by means of


title: Phonograph content: an "idler wheel" (see below). While light and cheap to manufacture, these mechanisms had low inertia, making motor speed instabilities more pronounced. Costlier turntables made from heavy aluminium castings have greater balanced mass and inertia, helping minimize vibration at the stylus, and maintaining constant speed without wow or flutter, even if the motor exhibits cogging effects. Like stamped steel turntables, they were topped with rubber. Because of the increased mass, they usually employed ball bearings or roller bearings in the spindle to reduce friction and noise. Most are belt or direct drive, but some use an idler wheel. A specific


title: Phonograph content: case was the Swiss "Lenco" drive, which possessed a very heavy turntable coupled via an idler wheel to a long, tapered motor drive shaft. This enabled stepless rotation or speed control on the drive. Because of this feature the Lenco became popular in the late 1950s with dancing schools, because the dancing instructor could lead the dancing exercises at different speeds. By the early 1980s, some companies started producing very inexpensive turntables that displaced the products of companies like BSR. Commonly found in "all-in-one" stereos from assorted far-east manufacturers, they used a thin plastic table set in a plastic plinth,


title: Phonograph content: no mats, belt drive, weak motors, and often, lightweight plastic tonearms with no counterweight. Most used sapphire pickups housed in ceramic cartridges, and they lacked several features of earlier units, such as auto-start and record-stacking. While not as common now that turntables are absent from the cheap "all-in-one" units, this type of turntable has made a strong resurgence in nostalgia-marketed record players. From the earliest phonograph designs, many of which were powered by spring-wound mechanisms, a speed governor was essential. Most of these employed some type of flywheel-friction disc to control the speed of the rotating cylinder or turntable; as


title: Phonograph content: the speed increased, centrifugal force caused a brake—often a felt pad—to rub against a smooth metal surface, slowing rotation. Electrically powered turntables, whose rotational speed was governed by other means, eventually made their mechanical counterparts obsolete. The mechanical governor was, however, still employed in some toy phonographs (such as those found in talking dolls) until they were replaced by digital sound generators in the late 20th century. Many modern players have platters with a continuous series of strobe markings machined or printed around their edge. Viewing these markings in artificial light at mains frequency produces a stroboscopic effect, which can


title: Phonograph content: be used to verify proper rotational speed. Additionally, the edge of the turntable can contain magnetic markings to provide feedback pulses to an electronic speed-control system. Earlier designs used a rubberized idler-wheel drive system. However, wear and decomposition of the wheel, as well as the direct mechanical coupling to a vibrating motor, introduced low-frequency noise ("rumble") and speed variations ("wow and flutter") into the sound. These systems generally used a synchronous motor which ran at a speed synchronized to the frequency of the AC power supply. Portable record players typically used an inexpensive shaded-pole motor. At the end of the


title: Phonograph content: motor shaft there was a stepped driving capstan; to obtain different speeds, the rubber idler wheel was moved to contact different steps of this capstan. The idler was pinched against the bottom or inside edge of the platter to drive it. Until the 1970s, the idler-wheel drive was the most common on turntables, except for higher-end audiophile models. However, even some higher-end turntables, such as the Lenco, Garrard, EMT, and Dual turntables, used idler-wheel drive. Belt drives brought improved motor and platter isolation compared to idler-wheel designs. Motor noise, generally heard as low-frequency rumble, is greatly reduced. The design of


title: Phonograph content: the belt drive turntable allows for a less expensive motor than the direct-drive turntable to be used. The elastomeric belt absorbs motor vibrations and noise which could otherwise be picked up by the stylus. It also absorbs small, fast speed variations, caused by "cogging", which in other designs are heard as "flutter." The "Acoustical professional" turntable (earlier marketed under Dutch ""Jobo prof"") of the 1960s however possessed an expensive German drive motor, the ""Pabst Aussenläufer"" ("Pabst outrunner"). As this motor name implied, the rotor was on the outside of the motor and acted as a flywheel ahead of the belt-driven


title: Phonograph content: turntable itself. In combination with a steel to nylon turntable bearing (with molybdenum disulfide inside for lifelong lubrication) very low wow, flutter and rumble figures were achieved. Direct-drive turntables drive the platter directly without utilizing intermediate wheels, belts, or gears as part of a drive train. The platter functions as a motor armature. This requires good engineering, with advanced electronics for acceleration and speed control. Matsushita's Technics division introduced the first commercially successful direct drive platter, model SP10, in 1969, which was joined by the Technics SL-1200 turntable, in 1972. Its updated model, SL-1200MK2, released in 1978, had a stronger


title: Phonograph content: motor, a convenient pitch control slider for beatmatching and a stylus illuminator, which made it the long-standing favourite among disc jockeys ("see "Turntablism""). By the beginnings of the 80s, lowering of costs in microcontroller electronics made direct drive turntables more affordable. The evaluation of the "best" drive technology is not clear and more depending on the implementation than on the drive technology itself. Technical measurements show that similarly low flutter (0.025% WRMS) and rumble (−78 dB weighed) figures are possible for high quality turntables, be they belt drive or direct drive. Audiophile grade turntables start at a few hundred dollars


title: Phonograph content: and range upwards of $100,000, depending on the complexity and quality of design and manufacture. The common view is that there are diminishing returns with an increase in price – a turntable costing $1,000 would not sound significantly better than a turntable costing $500; nevertheless, there exists a large choice of expensive turntables. The tone arm (or tonearm) holds the pickup cartridge over the groove, the stylus tracking the groove with the desired force to give the optimal compromise between good tracking and minimizing wear of the stylus and record groove. At its simplest, a tone arm is a pivoted


title: Phonograph content: lever, free to move in two axes (vertical and horizontal) with a counterbalance to maintain tracking pressure. However, the requirements of high-fidelity reproduction place more demands upon the arm design. In a perfect world: These demands are contradictory and impossible to realize (massless arms and zero-friction bearings do not exist in the real world), so tone arm designs require engineering compromises. Solutions vary, but all modern tonearms are at least relatively lightweight and stiff constructions, with precision, very low friction pivot bearings in both the vertical and horizontal axes. Most arms are made from some kind of alloy (the cheapest


title: Phonograph content: being aluminium), but some manufacturers use balsa wood, while others use carbon fiber or graphite. The latter materials favor a straight arm design; alloys' properties lend themselves to S-type arms. The tone arm got its name before the age of electronics. It originally served to conduct actual sound waves from a purely mechanical "pickup" called a "sound box" or "reproducer" to a so-described "amplifying" horn. The earliest electronic record players, introduced at the end of 1925, had massive electromagnetic pickups that contained a horseshoe magnet, used disposable steel needles, and weighed several ounces. Their full weight rested on the record,


title: Phonograph content: providing ample "tracking force" to overcome their low compliance but causing rapid record wear. The tone arms were rudimentary and remained so even after lighter crystal pickups appeared about ten years later. When fine-grooved vinyl records were introduced in the late 1940s, still smaller and lighter crystal (later, ceramic) cartridges with semi-permanent jewel styluses became standard. In the mid-1950s these were joined by a new generation of magnetic cartridges that bore little resemblance to their crude ancestors. Far smaller tracking forces became possible and the "balanced arm" came into use. Prices varied widely. The well-known and extremely popular high-end S-type


title: Phonograph content: SME arm of the 1970–1980 era not only had a complicated design, it was also very costly. On the other hand, even some cheaper arms could be of professional quality: the "All Balance" arm, made by the now-defunct Dutch company Acoustical, was only €30 [equivalent]. It was used during that period by all official radio stations in the Dutch Broadcast studio facilities of the NOS, as well as by the pirate radio station Veronica. Playing records from a boat in international waters, the arm had to withstand sudden ship movements. Anecdotes indicate this low-cost arm was the only one capable


title: Phonograph content: of keeping the needle firmly in the groove during heavy storms at sea. Quality arms employ an adjustable counterweight to offset the mass of the arm and various cartridges and headshells. On this counterweight, a calibrated dial enables easy adjustment of stylus force. After perfectly balancing the arm, the dial itself is "zeroed"; the stylus force can then be dialed in by screwing the counterweight towards the fulcrum. (Sometimes a separate spring or smaller weight provides fine tuning.) Stylus forces of 10 to 20 mN (1 to 2 grams-force) are typical for modern consumer turntables, while forces of up to


title: Phonograph content: 50 mN (5 grams) are common for the tougher environmental demands of party deejaying or turntablism. Of special adjustment consideration, Stanton cartridges of the 681EE(E) series [and others like them] feature a small record brush ahead of the cartridge. The upforce of this brush, and its added drag require compensation of both tracking force (add 1 gram) and anti-skating adjustment values (see next paragraph for description). Even on a perfectly flat LP, tonearms are prone to two types of tracking errors that affect the sound. As the tonearm tracks the groove, the stylus exerts a frictional force tangent to the


title: Phonograph content: arc of the groove, and since this force does not intersect the tone arm pivot, a clockwise rotational force (moment) occurs and a reaction "skating force" is exerted on the stylus by the record groove wall away from center of the disc. Modern arms provide an "anti-skate" mechanism, using springs, hanging weights, or magnets to produce an offsetting counter-clockwise force at the pivot, making the net lateral force on the groove walls near zero. The second error occurs as the arm sweeps in an arc across the disc, causing the angle between the cartridge head and groove to change slightly.


title: Phonograph content: A change in angle, albeit small, will have a detrimental effect (especially with stereo recordings) by creating different forces on the two groove walls, as well as a slight timing shift between left/right channels. Making the arm longer to reduce this angle is a partial solution, but less than ideal. A longer arm weighs more, and only an infinitely long [pivoted] arm would reduce the error to zero. Some designs (Burne-Jones, and Garrard "Zero" series) use dual arms in a parallelogram arrangement, pivoting the cartridge head to maintain a constant angle as it moves across the record. Unfortunately this "solution"


title: Phonograph content: creates more problems than it solves, compromising rigidity and creating sources of unwanted noise. The pivoted arm produces yet another problem which is unlikely to be significant to the audiophile, though. As the master was originally cut in a linear motion from the edge towards the center, but the stylus on the pivoted arm always draws an arc, this causes a timing drift that is most significant when digitizing music and beat mapping the data for synchronization with other songs in a DAW or DJ software unless the software allows building a non-linear beat map. As the contact point of


title: Phonograph content: the stylus on the record wanders farther from the linear path between the starting point and center hole, the tempo and pitch tend to decrease towards the middle of the record, until the arc reaches its apex. After that the tempo and pitch increase towards the end as the contact point comes closer to the linear path again. Because the surface speed of the record is lower at the end, the relative speed error from the same absolute distance error is higher at the end, and the increase in tempo is more notable towards the end than the decrease towards


title: Phonograph content: the middle. This can be somewhat reduced by a curved arm pivoted so that the end point of the arc stays farther from the linear path than the starting point, or by a long straight arm that pivots perpendicularly to the linear path in the middle of the record. However the tempo droop at the middle can only be completely avoided by a linear tracking arm. If the arm is not pivoted, but instead carries the stylus along a radius of the disc, there is no skating force and little to no cartridge angle error. Such arms are known as


title: Phonograph content: "linear tracking" or "tangential" arms. These are driven along a track by various means, from strings and pulleys, to worm gears or electromagnets. The cartridge's position is usually regulated by an electronic servomechanism or mechanical interface, moving the stylus properly over the groove as the record plays, or for song selection. There are long-armed and short-armed linear arm designs. On a perfectly flat record a short arm will do, but once the record is even slightly warped, a short arm will be troublesome. Any vertical motion of the record surface at the stylus contact point will cause the stylus to


title: Phonograph content: considerably move longitudinally in the groove. This will cause the stylus to ride non-tangentially in the groove and cause a stereo phase error as well as pitch error every time the stylus rides over the warp. Also the arm track can come into touch with the record. A long arm will not completely eliminate this problem but will tolerate warped records much better. Early developments in linear turntables were from Rek-O-Kut (portable lathe/phonograph) and Ortho-Sonic in the 1950s, and Acoustical in the early 1960s. These were eclipsed by more successful implementations of the concept from the late 1960s through the


title: Phonograph content: early 1980s. Of note are Rabco's SL-8, followed by Bang & Olufsen with its Beogram 4000 model in 1972. These models positioned the track outside the platter's edge, as did turntables by Harman Kardon, Mitsubishi, Pioneer, Yamaha, Sony, etc. A 1970s design from Revox harkened back to the 1950s attempts (and, record lathes), positioning the track directly over the record. An enclosed bridge-like assembly is swung into place from the platter's right edge to its middle. Once in place, a short tonearm under this "bridge" plays the record, driven across laterally by a motor. The Sony PS-F5/F9 (1983) uses a


title: Phonograph content: similar, miniaturized design, and can operate in a vertical or horizontal orientation. The Technics SL-10, introduced in 1981, was the first direct drive linear tracking turntable, and placed the track and arm on the underside of the rear-hinged dust cover, to fold down over the record, similar to the SL-Q6 pictured. The earliest Edison phonographs used horizontal, spring-powered drives to carry the stylus across the recording at a pre-determined rate. But, historically as a whole, the linear tracking systems never gained wide acceptance, due largely to their complexity and associated production/development costs. The resources it takes to produce one incredible


title: Phonograph content: linear turntable could produce several excellent ones. Some of the most sophisticated and expensive tonearms and turntable units ever made are linear trackers, from companies such as Rockport and Clearaudio. In theory, it seems nearly ideal; a stylus replicating the motion of the recording lathe used to cut the "master" record could result in minimal wear and maximum sound reproduction. In practice, in vinyl's heyday it was generally too much too late. Since the early 1980s, an elegant solution has been the near-frictionless air bearing linear arm that requires no tracking drive mechanism other than the record groove. This provides


title: Phonograph content: a similar benefit as the electronic linear tonearm without the complexity and necessity of servo-motor correction for tracking error. In this case the trade-off is the introduction of pneumatics in the form of audible pumps and tubing. A more elegant solution is the mechanically driven low-friction design, also driven by the groove. Examples include Souther Engineering (U.S.A.), Clearaudio (Germany), and Aura (Czech Republic). This design places an exceeding demand upon precision engineering due to the lack of pneumatics. Historically, most high-fidelity "component" systems (preamplifiers or receivers) that accepted input from a phonograph turntable had separate inputs for both ceramic and


title: Phonograph content: magnetic cartridges (typically labeled "CER" and "MAG"). One piece systems often had no additional phono inputs at all, regardless of type. Most systems today, if they accept input from a turntable at all, are configured for use only with magnetic cartridges. Manufacturers of high-end systems often have in-built moving coil amplifier circuitry, or outboard head-amplifiers supporting either moving magnet or moving coil cartridges that can be plugged into the line stage. Early electronic phonographs used a piezo-electric "crystal" for pickup (though the earliest electronic phonographs used crude magnetic pick-ups), where the mechanical movement of the stylus in the groove generates


title: Phonograph content: a proportional electrical voltage by creating stress within a crystal (typically Rochelle salt). Crystal pickups are relatively robust, and produce a substantial signal level which requires only a modest amount of further amplification. The output is not very linear however, introducing unwanted distortion. It is difficult to make a crystal pickup suitable for quality stereo reproduction, as the stiff coupling between the crystal and the long stylus prevents close tracking of the needle to the groove modulations. This tends to increase wear on the record, and introduces more distortion. Another problem is the hygroscopic nature of the crystal itself: it


title: Phonograph content: absorbs moisture from the air and may dissolve. The crystal was protected by embedding it in other materials, without hindering the movement of the pickup mechanism itself. After a number of years, the protective jelly often deteriorated or leaked from the cartridge case and the full unit needed replacement. The next development was the "ceramic" cartridge, a piezoelectric device that used newer, and better, materials. These were more sensitive, and offered greater "compliance", that is, lack of resistance to movement and so increased ability to follow the undulations of the groove without gross distorting or jumping out of the groove.


title: Phonograph content: Higher compliance meant lower tracking forces and reduced wear to both the disc and stylus. It also allowed ceramic stereo cartridges to be made. During the 1950s to 1970s, ceramic cartridge became common in low quality phonographs, but better high-fidelity (or "hi-fi") systems used magnetic cartridges, and the availability of low cost magnetic cartridges from the 1970s onwards made ceramic cartridges obsolete for essentially all purposes. At the seeming end of the market lifespan of ceramic cartridges, someone accidentally discovered that by terminating a specific ceramic mono cartridge (the Ronette TX88) not with the prescribed 47 kΩ resistance, but with


title: Phonograph content: approx. 10 kΩ, it could be connected to the moving magnet (MM) input too. The result, a much smoother frequency curve extended the lifetime for this popular and very cheap type. Another popular ceramic stereo cartridge was the Audio Technica model AT66, which because of its price performance ratio was favoured by many as an alternative to more expensive magnetic cartridges. There are two common designs for magnetic cartridges, moving magnet (MM) and moving coil (MC) (originally called "dynamic"). Both operate on the same physics principle of electromagnetic induction. The moving magnet type was by far the most common and


title: Phonograph content: more robust of the two, though audiophiles often claim that the moving coil system yields higher fidelity sound. In either type, the stylus itself, usually of diamond, is mounted on a tiny metal strut called a cantilever, which is suspended using a collar of highly compliant plastic. This gives the stylus the freedom to move in any direction. On the other end of the cantilever is mounted a tiny permanent magnet (moving magnet type) or a set of tiny wound coils (moving coil type). The magnet is close to a set of fixed pick-up coils, or the moving coils are


title: Phonograph content: held within a magnetic field generated by fixed permanent magnets. In either case, the movement of the stylus as it tracks the grooves of a record causes a fluctuating magnetic field, which causes a small electric current to be induced in the coils. This current closely follows the sound waveform cut into the record, and may be transmitted by wires to an electronic amplifier where it is processed and amplified in order to drive a loudspeaker. Depending upon the amplifier design, a phono-preamplifier may be necessary. In most moving magnet designs, the stylus itself is detachable from the rest of


title: Phonograph content: the cartridge so it can easily be replaced. There are three primary types of cartridge mounts. The most common type is attached using two small screws to a headshell that then plugs into the tonearm, while another is a standardized "P-mount" or "T4P" cartridge (invented by Technics in 1980 and adopted by other manufacturers) that plugs directly into the tonearm. Many P-mount cartridges come with adapters to allow them to be mounted to a headshell. The third type is used mainly in cartridges designed for DJ use and it has a standard round headshell connector. Some mass market turntables use


title: Phonograph content: a proprietary integrated cartridge that cannot be upgraded. An alternative design is the "moving iron" variation on moving magnet used by ADC, Grado, Stanton/Pickering 681 series, Ortofon OM and VMS series, and the MMC cartridge of Bang & Olufsen. In these units, the magnet itself sits behind the four coils and magnetises the cores of all four coils. The moving iron cross at the other end of the coils varies the gaps between itself and each of these cores, according to its movements. These variations lead to voltage variations as described above. Famous brands for magnetic cartridges are: Grado, Stanton/Pickering


title: Phonograph content: (681EE/EEE), B&O (MM types for its two, non-compatible generations of parallel arm design), Shure (V15 Type I to V), Audio-Technica, Nagaoka, Dynavector, Koetsu, Ortofon, Technics, Denon and ADC. Strain gauge or "semiconductor" cartridges do not generate a voltage, but act like a variable resistor, whose resistance directly depends on the movement of the stylus. Thus, the cartridge "modulates" an external voltage supplied by the (special) preamplifier. These pickups were marketed by Euphonics, Sao Win, and Panasonic/Technics, amongst others. The main advantages (compared to magnetic carts are): The main disadvantage is the need of a special preamplifier that supplies a steady


title: Phonograph content: current (typically 5mA) to the semiconductor elements and handles a special equalization than the one needed for magnetic cartridges. A high-end strain-gauge cartridge is currently sold by an audiophile company, with special preamplifiers available. Electrostatic cartridges were marketed by Stax in the 1950 and 1960 years. They needed individual operating electronics or preamplifiers. A few specialist laser turntables read the groove optically using a laser pickup. Since there is no physical contact with the record, no wear is incurred. However, this "no wear" advantage is debatable, since vinyl records have been tested to withstand even 1200 plays with no significant


title: Phonograph content: audio degradation, provided that it is played with a high quality cartridge and that the surfaces are clean. An alternative approach is to take a high-resolution photograph or scan of each side of the record and interpret the image of the grooves using computer software. An amateur attempt using a flatbed scanner lacked satisfactory fidelity. A professional system employed by the Library of Congress produces excellent quality. A smooth-tipped "stylus" (in popular usage often called a "needle" due to the former use of steel needles for the purpose) is used to play the recorded groove. A special chisel-like stylus is


title: Phonograph content: used to engrave the groove into the "master record". The stylus is subject to hard wear as it is the only small part that comes into direct contact with the spinning record. In terms of the pressure imposed on its minute areas of actual contact, the forces it must bear are enormous. There are three desired qualities in a stylus: first, that it faithfully follows the contours of the recorded groove and transmits its vibrations to the next part in the chain; second, that it does not damage the recorded disc; and third, that it is resistant to wear. A


title: Phonograph content: worn-out, damaged or defective stylus tip will degrade audio quality and injure the groove. Different materials for the stylus have been used over time. Thomas Edison introduced the use of sapphire in 1892 and the use of diamond in 1910 for his cylinder phonographs. The Edison Diamond Disc players (1912–1929), when properly played, hardly ever required the stylus to be changed. The styli for vinyl records were also made out of sapphire or diamond. A specific case is the specific stylus type of Bang & Olufsen's (B&O) moving magnet cartridge MMC 20CL, mostly used in parallel arm B&O turntables in


title: Phonograph content: the 4002/6000 series. It uses a sapphire stem on which a diamond tip is fixed by a special adhesive. A stylus tip mass as low as 0.3 milligram is the result and full tracking only requires 1 gram of stylus force, reducing record wear even further. Maximum distortion (2nd harmonic) fell below 0.6%. Other than the Edison and European Pathé disc machines, early disc players, both external horn and internal horn "Victrola" style models, normally used very short-lived disposable needles. The most common material was steel, although other materials such as copper, tungsten, bamboo and cactus were used. Steel needles


title: Phonograph content: needed to be replaced frequently, preferably after each use, due to their very rapid wear from bearing down heavily on the mildly abrasive shellac record. Rapid wear was an essential feature so that their imprecisely formed tips would be quickly worn into compliance with the groove's contours. Advertisements implored customers to replace their steel needles after each record side. Steel needles were inexpensive, e.g., a box of 500 for 50 US cents, and were widely sold in packets and small tins. They were available in different thicknesses and lengths. Thick, short needles produced strong, loud tones while thinner, longer needles


title: Phonograph content: produces softer, muted tones. In 1916, in the face of a wartime steel shortage, Victor introduced their "Tungs-Tone" brand extra-long-playing needle, which was advertised to play between 100 and 300 records. It consisted of a brass shank into which a very hard and strong tungsten wire, somewhat narrower than the standard record groove, had been fitted. The protruding wire wore down, but not out, until it was worn too short to use. Later in the 78 rpm era, hardened steel and chrome-plated needles came on the market, some of which were claimed to play 10 to 20 record sides each.


title: Phonograph content: When sapphires were introduced for the 78 rpm disc and the LP, they were made by tapering a stem and polishing the tip to a sphere with a radius of around 70 and 25 micrometers respectively. A sphere is not equal to the form of the cutting stylus and by the time diamond needles came to the market, a whole discussion was started on the effect of circular forms moving through a non-circular cut groove. It can be easily shown that vertical, so called "pinching" movements were a result and when stereophonic LPs were introduced, unwanted vertical modulation was recognized


title: Phonograph content: as a problem. Also, the needle started its life touching the groove on a very small surface, giving extra wear on the walls. Another problem is in the tapering along a straight line, while the side of the groove is far from straight. Both problems were attacked together: by polishing the diamond in a certain way that it could be made doubly elliptic. 1) the side was made into one ellipse as seen from behind, meaning the groove touched along a short line and 2) the ellipse form was also polished as seen from above and curvature in the direction


title: Phonograph content: of the groove became much smaller than 25 micrometers e.g. 13 micrometers. With this approach a number of irregularities were eliminated. Furthermore, the angle of the stylus, which used to be always sloping backwards, was changed into the forward direction, in line with the slope the original cutting stylus possessed. These styli were expensive to produce, but the costs were effectively offset by their extended lifespans. The next development in stylus form came about by the attention to the CD-4 quadraphonic sound modulation process, which requires up to 50 kHz frequency response, with cartridges like Technics EPC-100CMK4 capable of playback


title: Phonograph content: on frequencies up to 100 kHz. This requires a stylus with a narrow side radius, such as 5 µm (or 0.2 mil). A narrow-profile elliptical stylus is able to read the higher frequencies (greater than 20 kHz), but at an increased wear, since the contact surface is narrower. For overcoming this problem, the Shibata stylus was invented around 1972 in Japan by Norio Shibata of JVC, fitted as standard on quadraphonic cartridges, and marketed as an extra on some high-end cartridges. The Shibata-designed stylus offers a greater contact surface with the groove, which in turn means less pressure over the


title: Phonograph content: vinyl surface and thus less wear. A positive side effect is that the greater contact surface also means the stylus will read sections of the vinyl that were not touched (or "worn") by the common spherical stylus. In a demonstration by JVC records "worn" after 500 plays at a relatively very high 4.5 gf tracking force with a spherical stylus, played "as new" with the Shibata profile. Other advanced stylus shapes appeared following the same goal of increasing contact surface, improving on the Shibata. Chronologically: "Hughes" Shibata variant (1975), "Ogura" (1978), Van den Hul (1982). Such a stylus may be


title: Phonograph content: marketed as "Hyperelliptical" (Shure), "Alliptic", "Fine Line" (Ortofon), "Line contact" (Audio Technica), "Polyhedron", "LAC", or "Stereohedron" (Stanton). A keel-shaped diamond stylus appeared as a byproduct of the invention of the CED Videodisc. This, together with laser-diamond-cutting technologies, made possible the "ridge" shaped stylus, such as the Namiki (1985) design, and Fritz Gyger (1989) design. This type of stylus is marketed as "MicroLine" (Audio technica), "Micro-Ridge" (Shure), or "Replicant" (Ortofon). It is important to point out that most of those stylus profiles are still being manufactured and sold, together with the more common spherical and elliptical profiles. This is despite the


title: Phonograph content: fact that production of CD-4 quadraphonic records ended by the late 1970s. Early materials in the 19th century were hardened rubber, wax, and celluloid, but early in the 20th century a shellac compound became the standard. Since shellac is not hard enough to withstand the wear of steel needles on heavy tone arms, filler made of pulverized shale was added. Shellac was also fragile, and records often shattered or cracked. This was a problem for home records, but it became a bigger problem in the late 1920s with the Vitaphone sound-on-disc motion picture "talkie" system, developed in 1927. To solve


title: Phonograph content: this problem, in 1930, RCA Victor made unbreakable records by mixing polyvinyl chloride with plasticisers, in a proprietary formula they called Victrolac, which was first used in 1931, in motion picture discs, and experimentally, in home records, the same year. However, with Sound-on-film achieving supremacy over sound-on-disc by 1931, the need for unbreakable records diminished and the production of vinyl home recordings was dropped as well, for the time being. The Victrolac formula improved throughout the 1930s, and by the late 30s the material, by then called vinylite, was being used in records sent to radio stations for radio program


title: Phonograph content: records, radio commercials, and later, DJ copies of phonograph records, because vinyl records could be sent through the mail to radio stations without breaking. During WWII, there was a shortage of shellac, which had to be imported from Asia, and the U.S. government banned production of shellac records for the duration of the war. Vinylite was made domestically, though, and was being used for V-discs during the war. Record company engineers took a much closer look at the possibilities of vinyl, possibly that it might even replace shellac as the basic record material. After the war, RCA Victor and Columbia,


title: Phonograph content: by far the two leading records companies in America, perfected two new vinyl formats, which were both introduced in 1948, when the 33 RPM LP was introduced by Columbia and the 45 RPM single was introduced by RCA Victor. For a few years thereafter, however, 78 RPM records continued to be made in shellac until that format was phased out around 1958. Early "acoustical" record players used the stylus to vibrate a diaphragm that radiated the sound through a horn. Several serious problems resulted from this: The introduction of electronic amplification allowed these issues to be addressed. Records are made


title: Phonograph content: with boosted high frequencies and reduced low frequencies, which allow for different ranges of sound to be produced.. This reduces the effect of background noise, including clicks or pops, and also conserves the amount of physical space needed for each groove, by reducing the size of the low-frequency undulations. During playback, the high frequencies must be rescaled to their original, flat frequency response—known as "equalization"—as well as being amplified. A phono input of an amplifier incorporates such equalization as well as amplification to suit the very low level output from a modern cartridge. Most hi-fi amplifiers made between the 1950s


title: Phonograph content: and the 1990s and virtually all DJ mixers are so equipped. The widespread adoption of digital music formats, such as CD or satellite radio, has displaced phonograph records and resulted in phono inputs being omitted in most modern amplifiers. Some newer turntables include built-in preamplifiers to produce line-level outputs. Inexpensive and moderate performance discrete phono preamplifiers with RIAA equalization are available, while high-end audiophile units costing thousands of dollars continue to be available in very small numbers. Phono inputs are starting to reappear on amplifiers in the 2010s due to the vinyl revival. Since the late 1950s, almost all phono


title: Phonograph content: input stages have used the RIAA equalization standard. Before settling on that standard, there were many different equalizations in use, including EMI, HMV, Columbia, Decca FFRR, NAB, Ortho, BBC transcription, etc. Recordings made using these other equalization schemes will typically sound odd if they are played through a RIAA-equalized preamplifier. High-performance (so-called "multicurve disc") preamplifiers, which include multiple, selectable equalizations, are no longer commonly available. However, some vintage preamplifiers, such as the LEAK varislope series, are still obtainable and can be refurbished. Newer preamplifiers like the Esoteric Sound Re-Equalizer or the K-A-B MK2 Vintage Signal Processor are also available. These


title: Phonograph content: kinds of adjustable phono equalizers are used by consumers wishing to play vintage record collections (often the only available recordings of musicians of the time) with the equalization used to make them. Turntables continue to be manufactured and sold in the 2010s, although in small numbers. While some audiophiles still prefer the sound of vinyl records over that of digital music sources (mainly compact discs), they represent a minority of listeners. As of 2015 the sale of vinyl LP's has increased 49–50% percent from the previous year although small in comparison to the sale of other formats which although more


title: Phonograph content: units were sold (Digital Sales, CDs) the more modern formats experienced a decline in sales. The quality of available record players, tonearms, and cartridges has continued to improve, despite diminishing demand, allowing turntables to remain competitive in the high-end audio market. Vinyl enthusiasts are often committed to the refurbishment and sometimes tweaking of vintage systems. The chart on the right illustrates that users of one enthusiasts' forum post as many pictures of discontinued gear as they do of current models. Updated versions of the 1970s era Technics SL-1200 (production ceased in 2010) have remained an industry standard for DJs to


title: Phonograph content: the present day. Turntables and vinyl records remain popular in mixing (mostly dance-oriented) forms of electronic music, where they allow great latitude for physical manipulation of the music by the DJ. In hip hop music and occasionally in other genres, the turntable is used as a musical instrument by DJs, who use turntables along with a DJ mixer to create unique rhythmic sounds. Manipulation of a record as part of the music, rather than for normal playback or mixing, is called turntablism. The basis of turntablism, and its best known technique, is "scratching", pioneered by Grand Wizzard Theodore. It was


title: Phonograph content: not until Herbie Hancock's "Rockit" in 1983 that the turntablism movement was recognized in popular music outside of a hip hop context. In the 2010s, many hip hop DJs use DJ CD players or digital record emulator devices to create scratching sounds; nevertheless, some DJs still scratch with vinyl records. The laser turntable uses a laser as the pickup instead of a stylus in physical contact with the disk. It was conceived of in the late 1980s, although early prototypes were not of usable audio quality. Practical laser turntables are now being manufactured by ELPJ. They are favoured by record


title: Phonograph content: libraries and some audiophiles since they eliminate physical wear completely. Experimentation is in progress in retrieving the audio from old records by scanning the disc and analysing the scanned image, rather than using any sort of turntable. Although largely replaced since the introduction of the compact disc in 1982, record albums still sell in small numbers and are available through numerous sources. In 2008, LP sales grew by 90% over 2007, with 1.9 million records sold. USB turntables have a built-in audio interface, which transfers the sound directly to the connected computer. Some USB turntables transfer the audio without equalization,


title: Phonograph content: but are sold with software that allows the EQ of the transferred audio file to be adjusted. There are also many turntables on the market designed to be plugged into a computer via a USB port for needle dropping purposes. Responding to longtime calls by fans and disc jockeys, Panasonic Corp. said it is reviving Technics turntables–the series that remains a de facto standard player supporting nightclub music scenes. The new analog turntable, which would come with new direct-drive motor technologies that Panasonic says would improve the quality of sound, would be released sometime between April 2016 and March 2017,


title: Phonograph content: the Japanese electronics company announced on September 2, 2015. Phonograph The phonograph is a device for the mechanical recording and reproduction of sound. In its later forms, it is also called a gramophone (as a trademark since 1887, as a generic name in the UK since 1910) or, since the 1940s, a record player. The sound vibration waveforms are recorded as corresponding physical deviations of a spiral groove engraved, etched, incised, or impressed into the surface of a rotating cylinder or disc, called a "record". To recreate the sound, the surface is similarly rotated while a playback stylus traces the


title: Pencil content: Pencil A pencil is an implement for writing or drawing constructed of a narrow, solid pigment core inside a protective casing which prevents the core from being broken and/or from leaving marks on the user’s hand during use. Pencils create marks by physical abrasion, leaving behind a trail of solid core material that adheres to a sheet of paper or other surface. They are distinct from pens, which instead dispense liquid or gel ink onto the surface being marked. Most pencil cores are made of graphite powder mixed with a clay binder. Graphite pencils (traditionally known as 'lead pencils') are


title: Pencil content: used for both writing and drawing and produce durable grey or black marks that can be erased easily. Though writing is easily removable with an eraser, it is otherwise resistant to moisture, most chemicals, ultraviolet radiation and natural aging. Other types of pencil core are less widely used, such as charcoal pencils, which are mainly used by artists for drawing and sketching. Coloured pencils are sometimes used by teachers or editors to correct submitted texts, but are typically regarded as art supplies, especially those with waxy core binders that tend to smear on paper instead of erasing. Grease pencils have


title: Pencil content: a softer, crayon-like waxy core that can leave marks on smooth surfaces such as glass or porcelain. The most common type of pencil casing is of thin wood, usually hexagonal in section but sometimes cylindrical or triangular, permanently bonded to the core. Similar permanent casings may be constructed of other materials such as plastic or paper. To use the pencil, the casing must be carved or peeled off to expose the working end of the core as a sharp point. Mechanical pencils have more elaborate casings which are not permanently bonded to the core. Instead, the casing supports a separate,


title: Pencil content: mobile piece of pigment core that can be extended or retracted through the casing tip as needed; these pencil casings can be re-loaded with a new core (usually graphite) when necessary. "Pencil", from Old French "pincel", from Latin a "little tail" (see "penis"; "pincellus" is Latin from the post-classical period) originally referred to an artist's fine brush of camel hair, also used for writing before modern lead or chalk pencils. Though the archetypal pencil was an artist's brush, the stylus, a thin metal stick used for scratching in papyrus or wax tablets, was used extensively by the Romans and for


title: Pencil content: palm-leaf manuscripts. As a technique for drawing, the closest predecesor to the pencil was Silverpoint until in 1565 (some sources say as early as 1500), a large deposit of graphite was discovered on the approach to Grey Knotts from the hamlet of Seathwaite in Borrowdale parish, Cumbria, England. This particular deposit of graphite was extremely pure and solid, and it could easily be sawn into sticks. It remains the only large-scale deposit of graphite ever found in this solid form. Chemistry was in its infancy and the substance was thought to be a form of lead. Consequently, it was called


title: Pencil content: "plumbago" (Latin for "lead ore"). Because the pencil core is still referred to as "lead", or a "lead", many people have the misconception that the graphite in the pencil is lead, and the black core of pencils is still referred to as "lead", even though it never contained the element lead. The words for pencil in German ("bleistift"), Irish ("peann luaidhe"), Arabic (قلم رصاص "qalam raṣāṣ"), and some other languages literally mean "lead pen". The value of graphite would soon be realised to be enormous, mainly because it could be used to line the moulds for cannonballs; the mines were


title: Pencil content: taken over by the Crown and were guarded. When sufficient stores of graphite had been accumulated, the mines were flooded to prevent theft until more was required. The usefulness of graphite for pencils was discovered as well, but graphite for pencils had to be smuggled. The news of the usefulness of these early pencils spread far and wide, attracting the attention of artists all over the known world. Because graphite is soft, it requires some form of encasement. Graphite sticks were initially wrapped in string or sheepskin for stability. England would enjoy a monopoly on the production of pencils until


title: Pencil content: a method of reconstituting the graphite powder was found in 1662 in Italy. However, the distinctively square English pencils continued to be made with sticks cut from natural graphite into the 1860s. The town of Keswick, near the original findings of block graphite, still manufactures pencils, the factory also being the location of the Cumberland Pencil Museum. The meaning of "graphite writing implement" apparently evolved late in the 16th century. Around 1560, an Italian couple named Simonio and Lyndiana Bernacotti made what are likely the first blueprints for the modern, wood-encased carpentry pencil. Their version was a flat, oval, more


title: Pencil content: compact type of pencil. Their concept involved the hollowing out of a stick of juniper wood. Shortly thereafter, a superior technique was discovered: two wooden halves were carved, a graphite stick inserted, and the halves then glued together—essentially the same method in use to this day. The first attempt to manufacture graphite sticks from powdered graphite was in Nuremberg, Germany, in 1662. It used a mixture of graphite, sulphur, and antimony. English and German pencils were not available to the French during the Napoleonic Wars; France, under naval blockade imposed by Great Britain, was unable to import the pure graphite


title: Pencil content: sticks from the British Grey Knotts mines – the only known source in the world. France was also unable to import the inferior German graphite pencil substitute. It took the efforts of an officer in Napoleon's army to change this. In 1795, Nicolas-Jacques Conté discovered a method of mixing powdered graphite with clay and forming the mixture into rods that were then fired in a kiln. By varying the ratio of graphite to clay, the hardness of the graphite rod could also be varied. This method of manufacture, which had been earlier discovered by the Austrian Joseph Hardtmuth, the founder


title: Pencil content: of the Koh-I-Noor in 1790, remains in use. In 1802, the production of graphite leads from graphite and clay was patented by the Koh-I-Noor company in Vienna. In England, pencils continued to be made from whole sawn graphite. Henry Bessemer's first successful invention (1838) was a method of compressing graphite powder into solid graphite thus allowing the waste from sawing to be reused. American colonists imported pencils from Europe until after the American Revolution. Benjamin Franklin advertised pencils for sale in his "Pennsylvania Gazette" in 1729, and George Washington used a three-inch pencil when he surveyed the Ohio Territory in


title: Pencil content: 1762. It is said that William Munroe, a cabinetmaker in Concord, Massachusetts, made the first American wood pencils in 1812. This was not the only pencil-making occurring in Concord. According to Henry Petroski, transcendentalist philosopher Henry David Thoreau discovered how to make a good pencil out of inferior graphite using clay as the binder; this invention was prompted by his father's pencil factory in Concord, which employed graphite found in New Hampshire in 1821 by Charles Dunbar. Munroe's method of making pencils was painstakingly slow, and in the neighbouring town of Acton, a pencil mill owner named Ebenezer Wood set


title: Pencil content: out to automate the process at his own pencil mill located at Nashoba Brook. He used the first circular saw in pencil production. He constructed the first of the hexagon- and octagon-shaped wooden casings. Ebenezer did not patent his invention and shared his techniques with anyone. One of those was Eberhard Faber of New York, who became the leader in pencil production. Joseph Dixon, an inventor and entrepreneur involved with the Tantiusques granite mine in Sturbridge, Massachusetts, developed a means to mass-produce pencils. By 1870, The Joseph Dixon Crucible Company was the world’s largest dealer and consumer of graphite and


title: Pencil content: later became the contemporary Dixon Ticonderoga pencil and art supplies company. By the end of the 19th century, over 240,000 pencils were used each day in the US. The favoured timber for pencils was Red Cedar as it was aromatic and did not splinter when sharpened. In the early 20th century supplies of Red Cedar were dwindling so that pencil manufacturers were forced to recycle the wood from cedar fences and barns to maintain supply. One effect of this was that "during World War II rotary pencil sharpeners were outlawed in Britain because they wasted so much scarce lead and


title: Pencil content: wood, and pencils had to be sharpened in the more conservative manner – with knives." It was soon discovered that Incense cedar, when dyed and perfumed to resemble Red Cedar, was a suitable alternative and most pencils today are made from this timber which is grown in managed forests. Over 14 billion pencils are manufactured worldwide annually. Less popular alternatives to cedar include basswood and alder. In Southeast Asia the wood Jelutong may be used to create pencils (though the use of this rainforest species is controversial). Environmentalists prefer the use of Pulai – another wood native to the region


title: Pencil content: and used in pencil manufacturing. On 30 March 1858, Hymen Lipman received the first patent for attaching an eraser to the end of a pencil. In 1862, Lipman sold his patent to Joseph Reckendorfer for $100,000, who went on to sue pencil manufacturer Faber-Castell for infringement. In 1875, the Supreme Court of the US ruled against Reckendorfer declaring the patent invalid. Historian Henry Petroski notes that while ever more efficient means of mass production of pencils has driven the replacement cost of a pencil down, before this people would continue to use even the stub of a pencil. For those


title: Pencil content: who "did not feel comfortable using a stub, pencil extenders were sold. These devices function something like a "porte-crayon"...the pencil stub can be inserted into the end of a shaft...Extenders were especially common among engineers and draftsmen, whose favorite pencils were priced dearly. The use of an extender also has the advantage that the pencil does not appreciably change its heft as it wears down." Artists currently use extenders to maximize the use of their colored pencils. A standard, #2, hexagonal pencil is long. There are also pencils which use mechanical methods to push lead through a hole at the


title: Pencil content: end. These can be divided into two groups: propelling pencils use an internal mechanism to push the lead out from an internal compartment, while clutch pencils merely hold the lead in place (the lead is extended by releasing it and allowing some external force, usually gravity, to pull it out of the body). The erasers (sometimes replaced by a sharpener on pencils with larger lead sizes) are also removable (and thus replaceable), and usually cover a place to store replacement leads. Mechanical pencils are popular for their longevity and the fact that they may never need sharpening. Lead types are


title: Pencil content: based on grade and size; with standard sizes being , , , , , , , , and (ISO 9175-1)—the size is available, but is not considered a standard ISO size. Pioneered by Taiwanese stationery manufacturer Bensia Pioneer Industrial Corporation in the early 1970s, the product is also known as Bensia Pencils, stackable pencils or non-sharpening pencils. It is a type of pencil where many short pencil tips are housed in a cartridge-style plastic holder. A blunt tip is removed by pulling it from the writing end of the body and re-inserting it into the open-ended bottom of the body,


title: Pencil content: thereby pushing a new tip to the top. Invented by Harold Grossman for Empire Pencil Company in 1967 and subsequently improved upon by Arthur D. Little for Empire from 1969 through the early 1970s; the plastic pencil was commercialised by Empire as the "EPCON" Pencil. These pencils were co-extruded, extruding a plasticised graphite mix within a wood-composite core. Residual graphite from a pencil stick is not poisonous, and graphite is harmless if consumed. Although lead has not been used for writing since antiquity, lead poisoning from pencils was not uncommon. Until the middle of the 20th century the paint used


title: Pencil content: for the outer coating could contain high concentrations of lead, and this could be ingested when the pencil was sucked or chewed. The lead of the pencil is a mix of finely ground graphite and clay powders. Before the two substances are mixed, they are separately cleaned of foreign matter and dried in a manner that creates large square cakes. Once the cakes have fully dried, the graphite and the clay squares are mixed together using water. The amount of clay content added to the graphite depends on the intended pencil hardness (lower proportions of clay makes the core softer),


title: Pencil content: and the amount of time spent on grinding the mixture determines the quality of the lead. The mixture is then shaped into long spaghetti-like strings, straightened, dried, cut, and then tempered in a kiln. The resulting strings are dipped in oil or molten wax, which seeps into the tiny holes of the material and allows for the smooth writing ability of the pencil. A juniper or incense-cedar plank with several long parallel grooves is cut to fashion a "slat," and the graphite/clay strings are inserted into the grooves. Another grooved plank is glued on top, and the whole assembly is


title: Pencil content: then cut into individual pencils, which are then varnished or painted. Many pencils feature an eraser on the top and so the process is usually still considered incomplete at this point. Each pencil has a shoulder cut on one end of the pencil to allow for a metal ferrule to be secured onto the wood. A rubber plug is then inserted into the ferrule for a functioning eraser on the end of the pencil. Graphite pencils are made of a mixture of clay and graphite and their darkness varies from light grey to black: the more clay the harder the


title: Pencil content: pencil. There is a wide range of grades available, mainly for artists who are interested in creating a full range of tones from light grey to black. Engineers prefer harder pencils which allow for a greater control in the shape of the lead. Manufacturers distinguish their pencils by grading them, but there is no common standard. Two pencils of the same grade but different manufacturers will not necessarily make a mark of identical tone nor have the same hardness. Most manufacturers, and almost all in Europe, designate their pencils with the letters "H" (commonly interpreted as "hardness") to "B" (commonly


title: Pencil content: "blackness"), as well as "F" (usually taken to mean "fineness", although F pencils are no more fine or more easily sharpened than any other grade. Also known as "firm" in Japan). The standard writing pencil is graded "HB". This designation might have been first used in the early 20th century by Brookman, an English pencil maker. It used "B" for black and "H" for hard; a pencil's grade was described by a sequence or successive Hs or Bs such as "BB" and "BBB" for successively softer leads, and "HH" and "HHH" for successively harder ones. The Koh-i-Noor Hardtmuth pencil manufacturers


title: Pencil content: claim to have first used the HB designations, with "H" standing for Hardtmuth, "B" for the company's location of Budějovice, and "F" for Franz Hardtmuth, who was responsible for technological improvements in pencil manufacture. As of 2009, a set of pencils ranging from a very soft, black-marking pencil to a very hard, light-marking pencil usually ranges from softest to hardest as follows: Koh-i-noor offers twenty grades from 10H to 8B for its 1500 series; Mitsubishi Pencil offers twenty-two grades from 10H to 10B for its Hi-uni range; Derwent produces twenty grades from 9H to 9B for its graphic pencils and


title: Pencil content: Staedtler produces sixteen from 6H to 8B for its Mars Lumograph pencils. Numbers as designation were first used by Conté and later by John Thoreau, father of Henry David Thoreau, in the 19th century. Although Conté/Thoreau's equivalence table is widely accepted, not all manufacturers follow it; for example, Faber-Castell uses a different equivalence table in its "Grip 2001" pencils: 1 = 2B, 2 = B, 2½ = HB, 3 = H, 4 = 2H. Graded pencils can be used for a rapid test that provides relative ratings for a series of coated panels but can't be used to compare the


title: Pencil content: pencil hardness of different coatings. This test defines a "pencil hardness" of a coating as the grade of the hardest pencil that does not permanently mark the coating when pressed firmly against it at a 45 degree angle. For standardized measurements, there are Mohs hardness testing pencils on the market. The majority of pencils made in the US are painted yellow. According to Henry Petroski, this tradition began in 1890 when the L. & C. Hardtmuth Company of Austria-Hungary introduced their Koh-I-Noor brand, named after the famous diamond. It was intended to be the world's best and most expensive pencil,


title: Pencil content: and at a time when most pencils were either painted in dark colours or not at all, the Koh-I-Noor was yellow. As well as simply being distinctive, the colour may have been inspired by the Austro-Hungarian flag; it was also suggestive of the Orient at a time when the best-quality graphite came from Siberia. Other companies then copied the yellow colour so that their pencils would be associated with this high-quality brand, and chose brand names with explicit Oriental references, such as Mikado (renamed Mirado) and Mongol. Not all countries use yellow pencils. German and Brazilian pencils, for example, are


title: Pencil content: often green, blue or black, based on the trademark colours of Faber-Castell, a major German stationery company which has plants in those countries. In southern European countries, pencils tend to be dark red or black with yellow lines, while in Australia, they are red with black bands at one end. In India, the most common pencil colour scheme was dark red with black lines, and pencils with a large number of colour schemes are produced by various companies. Pencils are commonly round, hexagonal, or sometimes triangular in section. Carpenters' pencils are typically oval or rectangular, so they cannot easily roll


title: Pencil content: away during work. The following table lists the prominent manufacturers of wood-cased (including wood-free) pencils around the world. Pencil A pencil is an implement for writing or drawing constructed of a narrow, solid pigment core inside a protective casing which prevents the core from being broken and/or from leaving marks on the user’s hand during use. Pencils create marks by physical abrasion, leaving behind a trail of solid core material that adheres to a sheet of paper or other surface. They are distinct from pens, which instead dispense liquid or gel ink onto the surface being marked. Most pencil cores


title: "Peter principle" content: of the Seniority Factor: the next level up is often fully occupied, blocking the path to promotion. (Murdering one's immediate superiors can be an effective way of overcoming this obstacle, but as this is such a rare phenomenon it does not really affect Peter and Hull's assessment of Push.) Pull is far more effective, and refers to accelerated promotion brought about by the efforts of an employee's mentors or patrons. It is better to have as many patrons as possible, because each additional patron produces a multiplying effect on their combined effectiveness, as patrons reinforce their positive opinion of the


title: "Political party" content: office, or a prominent member of Congress in opposition (although a big-state governor may aspire to that role). Officially, each party has a chairman for its national committee who is a prominent spokesman, organizer and fund-raiser, but without the status of prominent elected office holders. In parliamentary democracies, on a regular, periodic basis, party conferences are held to elect party officers, although snap leadership elections can be called if enough members opt for such. Party conferences are also held in order to affirm party values for members in the coming year. American parties also meet regularly and, again, are more


title: Phosphate content: pH values. For a neutral pH, as in the cytosol, pH = 7.0 so that only and ions are present in significant amounts (62% , 38% . Note that in the extracellular fluid (pH = 7.4), this proportion is inverted (61% , 39% ). Phosphate can form many polymeric ions such as pyrophosphate), , and triphosphate, . The various metaphosphate ions (which are usually long linear polymers) have an empirical formula of and are found in many compounds. In biological systems, phosphorus is found as a free phosphate ion in solution and is called inorganic phosphate, to distinguish it from


title: Pixies content: "Head On", and "Debaser"; these were later released on the 2004 DVD "Pixies". Furthermore, a music video accompanied the release of their 2013 song, "Bagboy", as well an alternate video released on a later date. Videos have been made for all the songs in EP1. The videos for "Here Comes Your Man" and "Allison" were also released on "The Complete 'B' Sides". By "Bossanova", the band had developed a severe aversion to recording music videos, and Francis refused to lip-sync to them. For example, in the "Here Comes Your Man" video, both Black and Deal open their mouths wide instead


title: "Philadelphia Phillies" content: to be one of the best rivalries in the National League. The rivalry started when the Pittsburgh Pirates entered National League play in their fifth season of 1887, four years after the Phillies. The Phillies and the Pirates had remained together after the National League split into two divisions in 1969. During the period of two-division play (1969 to 1993), the two National League East division rivals won the two highest numbers of division championships, reigning exclusively as NL East champions in the 1970s and again in the early 1990s, the Pirates 9, the Phillies 6; together, the two teams'


title: Platypus content: Platypus The platypus ("Ornithorhynchus anatinus"), sometimes referred to as the duck-billed platypus, is a semiaquatic egg-laying mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young. The animal is the sole living representative of its family (Ornithorhynchidae) and genus ("Ornithorhynchus"), though a number of related species appear in the fossil record. The first scientists to examine a preserved platypus body (in 1799) judged it a fake, made of several animals sewn together. The


title: Platypus content: unusual appearance of this egg-laying, duck-billed, beaver-tailed, otter-footed mammal baffled European naturalists when they first encountered it, with some considering it an elaborate hoax. It is one of the few species of venomous mammals: the male platypus has a spur on the hind foot that delivers a venom capable of causing severe pain to humans. The unique features of the platypus make it an important subject in the study of evolutionary biology and a recognizable and iconic symbol of Australia; it has appeared as a mascot at national events and features on the reverse of the Australian twenty-cent coin. The


title: Platypus content: platypus is the animal emblem of the state of New South Wales. Until the early 20th century humans hunted the platypus for its fur, but it is now protected throughout its range. Although captive-breeding programs have had only limited success, and the platypus is vulnerable to the effects of pollution, it is not under any immediate threat. When the platypus was first encountered by Europeans in 1798, a pelt and sketch were sent back to Great Britain by Captain John Hunter, the second Governor of New South Wales. British scientists' initial hunch was that the attributes were a hoax. George


title: Platypus content: Shaw, who produced the first description of the animal in the "Naturalist's Miscellany" in 1799, stated it was impossible not to entertain doubts as to its genuine nature, and Robert Knox believed it might have been produced by some Asian taxidermist. It was thought that somebody had sewn a duck's beak onto the body of a beaver-like animal. Shaw even took a pair of scissors to the dried skin to check for stitches. The common name "platypus" is the latinisation of the Greek word ('), "flat-footed", from ('), "broad, wide, flat" and (""), "foot". Shaw assigned the species the Linnaean


title: Platypus content: name "Platypus anatinus" when he initially described it, but the genus term was quickly discovered to already be in use as the name of the wood-boring ambrosia beetle genus "Platypus". It was independently described as "Ornithorhynchus paradoxus" by Johann Blumenbach in 1800 (from a specimen given to him by Sir Joseph Banks) and following the rules of priority of nomenclature, it was later officially recognised as "Ornithorhynchus anatinus". The scientific name "Ornithorhynchus anatinus" is derived from (""), which literally means "bird snout" in Greek; and "anatinus", which means "duck-like" in Latin. There is no universally-agreed plural form of "platypus" in


title: Platypus content: the English language. Scientists generally use "platypuses" or simply "platypus". Colloquially, the term "platypi" is also used for the plural, although this is technically incorrect and a form of pseudo-Latin; the correct Greek plural would be "platypodes". Early British settlers called it by many names, such as "watermole", "duckbill", and "duckmole". The name "platypus" is occasionally prefixed with the adjective "duck-billed" to form "duck-billed platypus". In David Collins's account of the new colony 1788–1801, he describes coming across as "an amphibious animal, of the mole species". His account includes a drawing of the animal. The body and the broad, flat


title: Platypus content: tail of the platypus are covered with dense, brown fur that traps a layer of insulating air to keep the animal warm. The fur is waterproof, and the texture is akin to that of a mole. The platypus uses its tail for storage of fat reserves (an adaptation also found in animals such as the Tasmanian devil). The webbing on the feet is more significant on the front feet and is folded back when walking on land. The elongated snout and lower jaw are covered in soft skin, forming the bill. The nostrils are located on the dorsal surface of


title: Platypus content: the snout, while the eyes and ears are located in a groove set just back from it; this groove is closed when swimming. Platypuses have been heard to emit a low growl when disturbed and a range of other vocalisations have been reported in captive specimens. Weight varies considerably from , with males being larger than females; males average in total length, while females average , with substantial variation in average size from one region to another, and this pattern does not seem to follow any particular climatic rule and may be due to other environmental factors, such as predation


title: Platypus content: and human encroachment. The platypus has an average body temperature of about rather than the typical of placental mammals. Research suggests this has been a gradual adaptation to harsh environmental conditions on the part of the small number of surviving monotreme species rather than a historical characteristic of monotremes. Modern platypus young have three teeth in each of the maxillae (one premolar and two molars) and dentaries (three molars), which they lose before or just after leaving the breeding burrow; adults have heavily keratinised pads in their place. The first upper and third lower cheek teeth of platypus nestlings are


title: Platypus content: small, each having one principal cusp, while the other teeth have two main cusps. The platypus jaw is constructed differently from that of other mammals, and the jaw-opening muscle is different. As in all true mammals, the tiny bones that conduct sound in the middle ear are fully incorporated into the skull, rather than lying in the jaw as in cynodonts and other premammalian synapsids. However, the external opening of the ear still lies at the base of the jaw. The platypus has extra bones in the shoulder girdle, including an interclavicle, which is not found in other mammals. As


title: Platypus content: in many other aquatic and semiaquatic vertebrates, the bones show osteosclerosis, increasing their density to provide ballast. It has a reptilian gait, with the legs on the sides of the body, rather than underneath. When on land, it engages in knuckle-walking on its front feet, to protect the webbing between the toes. While both male and female platypuses are born with ankle spurs, only the male's spurs deliver venom, composed largely of defensin-like proteins (DLPs), three of which are unique to the platypus. The DLPs are produced by the immune system of the platypus. The function of defensins is to


title: Platypus content: cause lysis in pathogenic bacteria and viruses, but in platypuses they also are formed into venom for defense. Although powerful enough to kill smaller animals such as dogs, the venom is not lethal to humans, but the pain is so excruciating that the victim may be incapacitated. Oedema rapidly develops around the wound and gradually spreads throughout the affected limb. Information obtained from case histories and anecdotal evidence indicates the pain develops into a long-lasting hyperalgesia (a heightened sensitivity to pain) that persists for days or even months. Venom is produced in the crural glands of the male, which are


title: Platypus content: kidney-shaped alveolar glands connected by a thin-walled duct to a calcaneus spur on each hind limb. The female platypus, in common with echidnas, has rudimentary spur buds that do not develop (dropping off before the end of their first year) and lack functional crural glands. The venom appears to have a different function from those produced by nonmammalian species; its effects are not life-threatening to humans, but nevertheless powerful enough to seriously impair the victim. Since only males produce venom and production rises during the breeding season, it may be used as an offensive weapon to assert dominance during this


title: Platypus content: period. Similar spurs are found on many archaic mammal groups, indicating that this is an ancient characteristic for mammals as a whole, and not exclusive to the platypus or other monotremes. Monotremes (for the other species, see Echidna) are the only mammals (apart from at least one species of dolphin) known to have a sense of electroreception: they locate their prey in part by detecting electric fields generated by muscular contractions. The platypus's electroreception is the most sensitive of any monotreme. The electroreceptors are located in rostrocaudal rows in the skin of the bill, while mechanoreceptors (which detect touch) are


title: Platypus content: uniformly distributed across the bill. The electrosensory area of the cerebral cortex is contained within the tactile somatosensory area, and some cortical cells receive input from both electroreceptors and mechanoreceptors, suggesting a close association between the tactile and electric senses. Both electroreceptors and mechanoreceptors in the bill dominate the somatotopic map of the platypus brain, in the same way human hands dominate the Penfield homunculus map. The platypus can determine the direction of an electric source, perhaps by comparing differences in signal strength across the sheet of electroreceptors. This would explain the characteristic side-to-side motion of the animal's head while


title: Platypus content: hunting, seen also in the Hammerhead shark while foraging. The cortical convergence of electrosensory and tactile inputs suggests a mechanism that determines the distance of prey that, when they move, emit both electrical signals and mechanical pressure pulses. The platypus uses the difference between arrival times of the two signals to sense distance. Feeding by neither sight nor smell, the platypus closes its eyes, ears, and nose each time it dives. Rather, when it digs in the bottom of streams with its bill, its electroreceptors detect tiny electric currents generated by muscular contractions of its prey, so enabling it to


title: Platypus content: distinguish between animate and inanimate objects, which continuously stimulate its mechanoreceptors. Experiments have shown the platypus will even react to an "artificial shrimp" if a small electric current is passed through it. The evolution of monotreme electrolocation probably evolved in order to allow the animals to forage in murky waters, and may be tied to their tooth loss. The extinct "Obdurodon" was electroreceptive, but unlike the modern platypus it foraged pelagically. In recent studies it has been suggested that the eyes of the platypus are more similar to those of Pacific hagfish or Northern Hemisphere lampreys than to those of


title: Platypus content: most tetrapods. The eyes also contain double cones, which most mammals do not have. Although the platypus's eyes are small and not used under water, several features indicate that vision played an important role in its ancestors. The corneal surface and the adjacent surface of the lens is flat while the posterior surface of the lens is steeply curved, similar to the eyes of other aquatic mammals such as otters and sea-lions. A temporal (ear side) concentration of retinal ganglion cells, important for binocular vision, indicates a role in predation, while the accompanying visual acuity is insufficient for such activities.


title: Platypus content: Furthermore, this limited acuity is matched by a low cortical magnification, a small lateral geniculate nucleus and a large optic tectum, suggesting that the visual midbrain plays a more important role than the visual cortex like in some rodents. These features suggest that the platypus has adapted to an aquatic and nocturnal lifestyle, developing its electrosensory system at the cost of its visual system; an evolutionary process paralleled by the small number of electroreceptors in the short-beaked echidna, which dwells in dry environments, whilst the long-beaked echidna, which lives in moist environments, is intermediate between the other two monotremes. The


title: Platypus content: platypus is semiaquatic, inhabiting small streams and rivers over an extensive range from the cold highlands of Tasmania and the Australian Alps to the tropical rainforests of coastal Queensland as far north as the base of the Cape York Peninsula. Inland, its distribution is not well known; it is extinct in South Australia (apart from an introduced population on Kangaroo Island) and is no longer found in the main part of the Murray-Darling Basin, possibly due to the declining water quality brought about by extensive land clearing and irrigation schemes. Along the coastal river systems, its distribution is unpredictable; it


title: Platypus content: appears to be absent from some relatively healthy rivers, and yet maintains a presence in others, for example, the lower Maribyrnong, that are quite degraded. In captivity, platypuses have survived to 17 years of age, and wild specimens have been recaptured when 11 years old. Mortality rates for adults in the wild appear to be low. Natural predators include snakes, water rats, goannas, hawks, owls, and eagles. Low platypus numbers in northern Australia are possibly due to predation by crocodiles. The introduction of red foxes in 1845 for hunting may have had some impact on its numbers on the mainland.


title: Platypus content: The platypus is generally regarded as nocturnal and crepuscular, but individuals are also active during the day, particularly when the sky is overcast. Its habitat bridges rivers and the riparian zone for both a food supply of prey species, and banks where it can dig resting and nesting burrows. It may have a range of up to , with a male's home range overlapping those of three or four females. The platypus is an excellent swimmer and spends much of its time in the water foraging for food. When swimming, it can be distinguished from other Australian mammals by the


title: Platypus content: absence of visible ears. Uniquely among mammals, it propels itself when swimming by an alternate rowing motion of the front feet; although all four feet of the platypus are webbed, the hind feet (which are held against the body) do not assist in propulsion, but are used for steering in combination with the tail. The species is endothermic, maintaining its body temperature at about 32 °C (90 °F), lower than most mammals, even while foraging for hours in water below 5 °C (41 °F). Dives normally last around 30 seconds, but can last longer, although few exceed the estimated aerobic


title: Platypus content: limit of 40 seconds. Recovery at the surface between dives commonly takes from 10 to 20 seconds. When not in the water, the platypus retires to a short, straight resting burrow of oval cross-section, nearly always in the riverbank not far above water level, and often hidden under a protective tangle of roots. The average sleep time of a platypus is said to be as long as 14 hours per day, possibly because it eats crustaceans, which provide a high level of calories. The platypus is a carnivore: it feeds on annelid worms, insect larvae, freshwater shrimp, and freshwater yabby


title: Platypus content: that it digs out of the riverbed with its snout or catches while swimming. It uses cheek-pouches to carry prey to the surface, where it is eaten. The platypus needs to eat about 20% of its own weight each day, which requires it to spend an average of 12 hours daily looking for food. When the platypus was first encountered by European naturalists, they were divided over whether the female laid eggs. This was not confirmed until 1884, when William Hay Caldwell was sent to Australia, where, after extensive searching assisted by a team of 150 Aborigines, he managed to


title: Platypus content: discover a few eggs. Mindful of the high cost per word, Caldwell tersely wired London, "Monotremes oviparous, ovum meroblastic." That is, monotremes lay eggs, and the eggs are similar to those of reptiles in that only part of the egg divides as it develops. The species exhibits a single breeding season; mating occurs between June and October, with some local variation taking place between different populations across its range. Historical observation, mark-and-recapture studies, and preliminary investigations of population genetics indicate the possibility of both resident and transient members of populations, and suggest a polygynous mating system. Females are thought likely


title: Platypus content: to become sexually mature in their second year, with breeding confirmed still to take place in animals over nine years old. Outside the mating season, the platypus lives in a simple ground burrow, the entrance of which is about above the water level. After mating, the female constructs a deeper, more elaborate burrow up to long and blocked at intervals with plugs (which may act as a safeguard against rising waters or predators, or as a method of regulating humidity and temperature). The male takes no part in caring for its young, and retreats to his year-long burrow. The female


title: Platypus content: softens the ground in the burrow with dead, folded, wet leaves, and she fills the nest at the end of the tunnel with fallen leaves and reeds for bedding material. This material is dragged to the nest by tucking it underneath her curled tail. The female platypus has a pair of ovaries, but only the left one is functional. The platypus's genes are a possible evolutionary link between the mammalian XY and bird/reptile ZW sex-determination systems because one of the platypus's five X chromosomes contains the DMRT1 gene, which birds possess on their Z chromosome. It lays one to three


title: Platypus content: (usually two) small, leathery eggs (similar to those of reptiles), about in diameter and slightly rounder than bird eggs. The eggs develop "in utero" for about 28 days, with only about 10 days of external incubation (in contrast to a chicken egg, which spends about one day in tract and 21 days externally). After laying her eggs, the female curls around them. The incubation period is divided into three phases. In the first phase, the embryo has no functional organs and relies on the yolk sac for sustenance. The yolk is absorbed by the developing young. During the second phase,


title: Platypus content: the digits develop, and in the last phase, the egg tooth appears. Most mammal zygotes go through holoblastic cleavage, meaning that following fertilization the ovum is split due to cell divisions into multiple, divisible daughter cells. This is in comparison to the more ancestral process of meroblastic division in non-mammals (including platypuses), which causes the ovum to split but not completely. This causes the cells at the edge of the yolk to be cytoplasmically continuous with the egg’s cytoplasm. This allows the yolk, which contains the embryo, to exchange waste and nutrients with the cytoplasm. The newly hatched young are


title: Platypus content: vulnerable, blind, and hairless, and are fed by the mother's milk. Although possessing mammary glands, the platypus lacks teats. Instead, milk is released through pores in the skin. The milk pools in grooves on her abdomen, allowing the young to lap it up. After they hatch, the offspring are suckled for three to four months. During incubation and weaning, the mother initially leaves the burrow only for short periods, to forage. When doing so, she creates a number of thin soil plugs along the length of the burrow, possibly to protect the young from predators; pushing past these on her


title: Platypus content: return forces water from her fur and allows the burrow to remain dry. After about five weeks, the mother begins to spend more time away from her young and, at around four months, the young emerge from the burrow. A platypus is born with teeth, but these drop out at a very early age, leaving the horny plates it uses to grind food. The platypus and other monotremes were very poorly understood, and some of the 19th century myths that grew up around them—for example, that the monotremes were "inferior" or quasireptilian—still endure. In 1947, William King Gregory theorised that