Master of ceremonies
A master of ceremonies, abbreviated MC, is the official host of a ceremony, staged event or similar performance. The term is earliest documented in the Catholic Church since the 5th century, where the Master of Ceremonies was and still is an official of the Papal Court responsible for the proper and smooth conduct of the elegant and elaborate rituals involving the Pope and the sacred liturgy; the master of ceremonies sometimes refers to the protocol officer during an official state function in monarchies. Today, the term is used to connote a compère, which corresponds to a master of ceremonies who presents performers, speaks to the audience, entertains people, keeps an event moving; this usage occurs in the entertainment industry, including for television game show hosts, as well as in contemporary hip hop and electronic dance music culture. In addition, the term exists in various chivalric orders and fraternal orders. Alternative names include compère, microphone controller; the term originated in the Catholic Church.
The Master of Ceremonies is an official of the Papal Court responsible for the proper and smooth conduct of the elegant and elaborate rituals involving the Pope and the sacred liturgy. He may be an official involved in the proper conduct of protocols and ceremonials involving the Roman Pontiff, the Papal Court, other dignitaries and potentates. Examples of official liturgical books prescribing the rules and regulations of liturgical celebrations are Cæremoniale Romanum and Cæremoniale Episcoporum; the office of the Master of Ceremonies itself is old. According to the Catholic Encyclopedia, the most ancient ceremonials and rituals of the Catholic Church are the Ordines Romani. Names of Masters of Ceremonies are known since the Renaissance. However, copies of books prescribing the forms of rituals and customs of pontifical ceremonies are known to have been given to Charles Martel in the 8th century; the rules and rituals themselves are known to have been compiled or written by the pontifical masters of ceremonies, dating back to the time of Pope Gelasius I with modifications and additions made by Pope Gregory the Great.
It is reasonable to assume. The duties of the Master of Ceremonies may have developed from the time Emperor Constantine the Great gave the Lateran Palace to the popes or from the time Christianity became the official religion of the Roman Empire, were no doubt influenced by imperial practices and norms. However, documentary evidence from the late Roman period is scarce or lost; the ceremonies and practices of the Byzantine emperors are known to have influenced the papal court. The accumulation of elaborations and complications since the Renaissance and Baroque eras continued well into the 20th century, until some of the ceremonies were simplified or eliminated by Pope Paul VI in the 1970s after Vatican II. At a large Catholic church or cathedral, the Master of Ceremonies organizes and rehearses the proceedings and ritual of each Mass, he may have responsibility for the physical security of the place of worship during the liturgy. At major festivities such as Christmas and Easter, when the liturgies are long and complex, the Master of Ceremonies plays a vital role in ensuring that everything runs smoothly.
The current papal Master of Ceremonies is Monsignor Guido Marini, who succeeded Archbishop Piero Marini. Certain European royal courts maintained senior offices known as Masters of Ceremonies, responsible for conducting stately ceremonies such as coronations and receptions of foreign ambassadors. Examples included: Spanish Empire: Maestro de Ceremonias British Empire: Master of the Ceremonies France: Grand Master of Ceremonies Japan: Master of Ceremonies Russian Empire: see Table of Ranks Ottoman Empire: Kapıcıbaşı "chief doorkeeper" of the Topkapi Palace The function is prevalent in the culture of chivalric orders, as well as in more modern fraternal orders, such as Freemasons and Odd Fellows. Most large corporate and association conferences and conventions use an MC to keep the events running smoothly; this role is sometimes performed by someone inside the group but by an outside professional expert MC. Their role could include - introducing and thanking speakers, introducing the theme of the conference, facilitating a panel discussion & interviewing guests.
During the wedding reception, the multifaceted responsibility of the Master of Ceremony is to keep the agenda flowing smoothly by: skillfully capturing and maintaining the attention of the wedding guests directing their attention on whatever the bride and groom have chosen to include keeping the wedding attendees informed so at any given moment they know what is happening comfortably guiding the bride's and groom's friends and family so they know what they are supposed to do to participateThe role of the wedding master of ceremonies incorporates a wide range of skills, those who serve in this capacity have undergone extensive training in the following areas: Delivering applause cues Presenting introductions Microphone technique Posture and stance Voice inflection Staging Masters of ceremonies at weddings and private events ensure the coordination of their event, including liaison with catering staff. In hip hop and electronic dance music, "MC" refers to rap artists or performers who perform vocals for their own or other artist's original material
Equalization or equalisation is the process of adjusting the balance between frequency components within an electronic signal. The most well known use of equalization is in sound recording and reproduction but there are many other applications in electronics and telecommunications; the circuit or equipment used to achieve equalization is called an equalizer. These devices strengthen or weaken the energy of specific frequency bands or "frequency ranges". In sound recording and reproduction, equalization is the process used to alter the frequency response of an audio system using linear filters. Most hi-fi equipment uses simple filters to make bass and treble adjustments. Graphic and parametric equalizers have much more flexibility in tailoring the frequency content of an audio signal. Since equalizers "adjust the amplitude of audio signals at particular frequencies," they are, "in other words, frequency-specific volume knobs."In the field of audio electronics, the term "equalization" has come to include the adjustment of frequency responses for practical or aesthetic reasons resulting in a net response, not "flat".
The term EQ refers to this variant of the term. Stereos and basic guitar amplifiers have adjustable equalizers which boost or cut bass or treble frequencies. Mid- to high-priced guitar and bass amplifiers have more bands of frequency control, such as bass, mid-range and treble or bass, low-mid, high-mid, treble; some amps have an additional knob for controlling high frequencies. Broadcast and recording studios use sophisticated equalizers capable of much more detailed adjustments, such as eliminating unwanted sounds or making certain instruments or voices more prominent. Equalizers are used in recording studios, radio studios and production control rooms, live sound reinforcement and in instrument amplifiers, such as guitar amplifiers, to correct or adjust the response of microphones, instrument pick-ups and hall acoustics. Equalization may be used to eliminate or reduce unwanted sounds, make certain instruments or voices more prominent, enhance particular aspects of an instrument's tone, or combat feedback in a public address system.
Equalizers are used in music production to adjust the timbre of individual instruments and voices by adjusting their frequency content and to fit individual instruments within the overall frequency spectrum of the mix. The most common equalizers in music production are parametric, semi-parametric, graphic and program equalizers. Graphic equalizers are included in consumer audio equipment and software which plays music on home computers. Parametric equalizers require more expertise than graphic equalizers, they can provide more specific compensation or alteration around a chosen frequency; this may be used in order to boost certain frequencies. For example, an acoustic guitarist who finds that her instrument sounds too "boomy" may ask the audio engineer to cut the low frequencies to correct this issue; the concept of equalization was first applied in correcting the frequency response of telephone lines using passive networks. Equalization was used to "compensate for" the uneven frequency response of an electric system by applying a filter having the opposite response, thus restoring the fidelity of the transmission.
A plot of the system's net frequency response would be a flat line, as its response at any frequency would be equal to its response at any other frequency. Hence the term "equalization." Much the concept was applied in audio engineering to adjust the frequency response in recording and live sound reinforcement systems. Sound engineers correct the frequency response of a sound system so that the frequency balance of the music as heard through speakers better matches the original performance picked up by a microphone. Audio amplifiers have long had controls to modify their frequency response; these are most in the form of variable bass and treble controls, switches to apply low-cut or high-cut filters for elimination of low frequency "rumble" and high frequency "hiss" respectively. Graphic equalizers and other equipment developed for improving fidelity have since been used by recording engineers to modify frequency responses for aesthetic reasons. Hence in the field of audio electronics the term "equalization" is now broadly used to describe the application of such filters regardless of intent.
This broad definition therefore includes all linear filters at the disposal of a listener or engineer. A British EQ or British style equalizer is one with similar properties to those on consoles made in the UK by companies such as Amek and Soundcraft from the 1950s through to the 1970s. On, as other manufacturers started to market their products, these British companies began touting their equalizers as being a cut above the rest. Today, many non-British companies such as Behringer and Mackie advertise British EQ on their equipment. A British style EQ seeks to replicate the qualities of the expensive British mixing consoles. Filtering audio frequencies dates back at least to acoustic telegraphy and multiplexing in general. Audio electronic equipment evolved to incorporate filtering elements as consoles in radio stations began to be used for recording as much as broadcast. Early filters included basic bass and treble controls featuring fixed frequency centers, fixed levels of cut or boost; these filters
A loudspeaker enclosure or loudspeaker cabinet is an enclosure in which speaker drivers and associated electronic hardware, such as crossover circuits and, in some cases, power amplifiers, are mounted. Enclosures may range in design from simple, homemade DIY rectangular particleboard boxes to complex, expensive computer-designed hi-fi cabinets that incorporate composite materials, internal baffles, bass reflex ports and acoustic insulation. Loudspeaker enclosures range in size from small "bookshelf" speaker cabinets with 4" woofers and small tweeters designed for listening to music with a hi-fi system in a private home to huge, heavy subwoofer enclosures with multiple 18" or 21" speakers in huge enclosures which are designed for use in stadium concert sound reinforcement systems for rock music concerts; the primary role of the enclosure is to prevent sound waves generated by the rearward-facing surface of the diaphragm of an open speaker driver interacting with sound waves generated at the front of the speaker driver.
Because the forward- and rearward-generated sounds are out of phase with each other, any interaction between the two in the listening space creates a distortion of the original signal as it was intended to be reproduced. As such, a loudspeaker cannot be used without installing it in a cabinet of some type, or mounting it into a wall or ceiling. Additionally, because the sound waves would travel different paths through the listening space, the sound waves in an unmounted speaker would arrive at the listener's position at different times, introducing echo and reverberation effects not part of the original sound; the enclosure plays a role in managing vibration induced by the driver frame and moving airmass within the enclosure, as well as heat generated by driver voice coils and amplifiers. Sometimes considered part of the enclosure, the base, may include specially designed "feet" to decouple the speaker from the floor. Enclosures designed for use in PA systems, sound reinforcement systems and for use by electric musical instrument players.
Speaker enclosures designed for use in a home or recording studio do not have handles or corner protectors, although they do still have a cloth or mesh cover to protect the woofer and tweeter. These speaker grilles are a metallic or cloth mesh that are used to protect the speaker by forming a protective cover over the speaker's cone while allowing sound to pass through undistorted. Speaker enclosures are used in homes in stereo systems, home cinema systems, boom boxes and many other audio appliances. Small speaker enclosures are used in car stereo systems. Speaker cabinets are key components of a number of commercial applications, including sound reinforcement systems, movie theatre sound systems and recording studios. Electric musical instruments invented in the 20th century, such as the electric guitar, electric bass and synthesizer, among others, are amplified using instrument amplifiers and speaker cabinets. Early on, radio loudspeakers consisted of horns sold separately from the radio itself, so they were not housed in an enclosure.
When paper cone loudspeaker drivers were introduced in the mid 1920s, radio cabinets began to be made larger to enclose both the electronics and the loudspeaker. These cabinets were made for the sake of appearance, with the loudspeaker mounted behind a round hole in the cabinet, it was observed. Since the rear of the loudspeaker radiates sound out of phase from the front, there can be constructive and destructive interference for loudspeakers without enclosures, below frequencies related to the baffle dimensions in open-baffled loudspeakers; this results in a loss of comb filtering. Before the 1950s many manufacturers did not enclose their loudspeaker cabinets; this was done for several reasons, not least because electronics could be placed inside and cooled by convection in the open enclosure. Most of the enclosure types discussed in this article were invented either to wall off the out of phase sound from one side of the driver, or to modify it so that it could be used to enhance the sound produced from the other side.
However, a few designs have ventured in a different direction, attempting to incorporate the natural acoustic properties of the cabinet material rather than deaden it, shape the cabinet so that the rear can remain open and still provide good bass response with limited comb filtering. In some respects, the ideal mounting for a low-frequency loudspeaker driver would be a rigid flat panel of infinite size with infinite space behind it; this would prevent the rear sound waves from interfering with the sound waves from the front. An "open baffle" loudspeaker is an approximation of this, since the driver is mounted on a panel, with dimensions comparable to the lowest wavelength to be reproduced. In either case, the driver would need a stiff suspension to provide the restoring force which might have been provided at low frequencies by a smaller sealed or ported enclosure, so few drivers are suitable for this kind of mount
A rave is an organized dance party at a nightclub, outdoor festival, warehouse, or other private property featuring performances by DJs, playing a seamless flow of electronic dance music. DJs at rave events play electronic dance music on vinyl, CDs and digital audio from a wide range of genres, including techno, house, drum & bass and post-industrial. Live performers have been known to perform, in addition to other types of performance artists such as go-go dancers and fire dancers; the music is amplified with a large, powerful sound reinforcement system with large subwoofers to produce a deep bass sound. The music is accompanied by laser light shows, projected coloured images, visual effects and fog machines. While some raves may be small parties held at nightclubs or private homes, some raves have grown to immense size, such as the large festivals and events featuring multiple DJs and dance areas; some electronic dance music festivals have features of raves, but on a larger commercial scale.
Raves may last for a long time, with some events continuing for twenty-four hours, lasting all through the night. Law enforcement raids and anti-rave laws have presented a challenge to the rave scene in many countries; this is due to the association of illegal drugs such as MDMA, LSD, GHB, methamphetamine and cannabis. In addition to drugs, raves make use of non-authorized, secret venues, such as squat parties at unoccupied homes, unused warehouses, or aircraft hangars; these concerns are attributed to a type of moral panic surrounding rave culture. In the late 1950s in London, England the term "rave" was used to describe the "wild bohemian parties" of the Soho beatnik set. Jazz musician Mick Mulligan, known for indulging in such excesses, had the nickname "king of the ravers". In 1958, Buddy Holly recorded the hit "Rave On", citing the madness and frenzy of a feeling and the desire for it never to end; the word "rave" was used in the burgeoning mod youth culture of the early 1960s as the way to describe any wild party in general.
People who were gregarious party animals were described as "ravers". Pop musicians such as Steve Marriott of The Small Faces and Keith Moon of The Who were self-described "ravers". Presaging the word's subsequent 1980s association with electronic music, the word "rave" was a common term used regarding the music of mid-1960s garage rock and psychedelia bands. Along with being an alternative term for partying at such garage events in general, the "rave-up" referred to a specific crescendo moment near the end of a song where the music was played faster and with intense soloing or elements of controlled feedback, it was part of the title of an electronic music performance event held on 28 January 1967 at London's Roundhouse titled the "Million Volt Light and Sound Rave". The event featured the only known public airing of an experimental sound collage created for the occasion by Paul McCartney of The Beatles – the legendary Carnival of Light recording. With the rapid change of British pop culture from the mod era of 1963–1966 to the hippie era of 1967 and beyond, the term fell out of popular usage.
During the 1970s and early 1980s until its resurrection, the term was not in vogue, one notable exception being in the lyrics of the song "Drive-In Saturday" by David Bowie which includes the line, "It's a crash course for the ravers." Its use during that era would have been perceived as a quaint or ironic use of bygone slang: part of the dated 1960s lexicon along with words such as "groovy". The perception of the word "rave" changed again in the late 1980s when the term was revived and adopted by a new youth culture inspired by the use of the term in Jamaica. In the mid to late 1980s, a wave of psychedelic and other electronic dance music, most notably acid house music, emerged from acid house music parties in the mid-to-late 1980s in the Chicago area in the United States. After Chicago acid house artists began experiencing overseas success, acid house spread and caught on in the United Kingdom within clubs and free-parties, first in Manchester in the mid-1980s and later in London. In the late 1980s, the word "rave" was adopted to describe the subculture that grew out of the acid house movement.
Activities were related to the party atmosphere of Ibiza, a Mediterranean island in Spain, frequented by British, Greek and German youth on vacation, who would hold raves and dance parties. By the 1990s, genres such as acid, breakbeat hardcore, happy hardcore, post-industrial and electronica were all being featured at raves, both large and small. There were mainstream events. Acid house music parties were first re-branded "rave parties" in the media, during the summer of 1989 by Genesis P-Orridge during a television interview. In 1990, raves were held "underground" in several cities, such as Berlin and Patras, in basements and forests. British politicians responded with hostility to the emerging rave party trend. Politicians began to fine promoters who held unauthorized parties. Police crackdowns on these unauthorized parties drove the rave scene into the countryside; the word "rave" somehow caught on in the UK to describe common semi-spontaneous weekend parties occurring at vario
Electronic dance music
Electronic dance music known as dance music, club music, or dance, is a broad range of percussive electronic music genres made for nightclubs and festivals. It is produced for playback by disc jockeys who create seamless selections of tracks, called a mix by segueing from one recording to another. EDM producers perform their music live in a concert or festival setting in what is sometimes called a live PA. In Europe, EDM is more called'dance music', or simply'dance'. In the late 1980s and early 1990s, following the emergence of raving, pirate radios and an upsurge of interest in club culture, EDM achieved widespread mainstream popularity in Europe. In the United States at that time, acceptance of dance culture was not universal. There was a perceived association between EDM and drug culture, which led governments at state and city level to enact laws and policies intended to halt the spread of rave culture. Subsequently, in the new millennium, the popularity of EDM increased globally in Australia and the United States.
By the early 2010s, the term "electronic dance music" and the initialism "EDM" was being pushed by the American music industry and music press in an effort to rebrand American rave culture. Despite the industry's attempt to create a specific EDM brand, the initialism remains in use as an umbrella term for multiple genres, including house, trance and bass and dubstep, as well as their respective subgenres. Various EDM genres have evolved for example. Stylistic variation within an established EDM genre can lead to the emergence of what is called a subgenre. Hybridization, where elements of two or more genres are combined, can lead to the emergence of an new genre of EDM. In the late 1960s bands such as Silver Apples created electronic music, intended to be danced to. Other early examples of music that influenced electronic dance music include Jamaican dub music during the late 1960s to 1970s, the synthesizer-based disco music of Italian producer Giorgio Moroder in the late 1970s, the electro-pop of Kraftwerk and Yellow Magic Orchestra in the mid-to-late 1970s.
Author Michael Veal considers dub music, a Jamaican music stemming from roots reggae and sound system culture that flourished between 1968 and 1985, to be one of the important precursors to contemporary electronic dance music. Dub productions were remixed reggae tracks that emphasized rhythm, fragmented lyrical and melodic elements, reverberant textures; the music was pioneered by studio engineers, such as Sylvan Morris, King Tubby, Errol Thompson, Lee "Scratch" Perry, Scientist. Their productions included forms of tape editing and sound processing that Veal considers comparable to techniques used in musique concrète. Dub producers made improvised deconstructions of existing multi-track reggae mixes by using the studio mixing board as a performance instrument, they foregrounded spatial effects such as reverb and delay by using auxiliary send routings creatively. The Roland Space Echo, manufactured by Roland Corporation, was used by dub producers in the 1970s to produce echo and delay effects.
Despite the limited electronic equipment available to dub pioneers such as King Tubby and Lee "Scratch" Perry, their experiments in remix culture were musically cutting-edge. Ambient dub was pioneered by King Tubby and other Jamaican sound artists, using DJ-inspired ambient electronics, complete with drop-outs, echo and psychedelic electronic effects, it featured layering techniques and incorporated elements of world music, deep bass lines and harmonic sounds. Techniques such as a long echo delay were used. Hip hop music has played a key role in the development of electronic dance music since the 1970s. Inspired by Jamaican sound system culture Jamaican-American DJ Kool Herc introduced large bass heavy speaker rigs to the Bronx, his parties are credited with having kick-started the New York hip-hop movement in 1973. A technique developed by DJ Kool Herc that became popular in hip hop culture was playing two copies of the same record on two turntables, in alternation, at the point where a track featured a break.
This technique was further used to manually loop a purely percussive break, leading to what was called a break beat. Turntablism has origins in the invention of the direct-drive turntable, by Shuichi Obata, an engineer at Matsushita. In 1969, Matsushita released it as the SP-10, the first direct-drive turntable on the market, the first in their influential Technics series of turntables; the most influential turntable was the Technics SL-1200, developed in 1971 by a team led by Shuichi Obata at Matsushita, which released it onto the market in 1972. In the 1980s and 1990s hip-hop DJs used turntables as musical instruments in their own right and virtuosic use developed into a creative practice called turntablism. In 1974, George McCrae's early disco hit "Rock Your Baby" was one of the first records to use a drum machine, an early Roland rhythm machine, its use of a drum machine was anticipated by Sly and the Family Stone's "Family Affair", which anticipated the sound of disco, with its rhythm echoed in "Rock Your Baby".
The use of drum machines in "Family Affair" and Timmy Thomas' "Why Can't We Live Together", which used a 1972 Roland rhythm machine, influenced the adoption of drum machines by disco artists. Disco producer Biddu used synthesizers in several disco songs from 1976 to 1977, including "Bionic Boogie" from Rain Forest, "Soul Coaxing", and
An audio tape recorder, tape deck, or tape machine is a sound recording and reproduction device that records and plays back sounds using magnetic tape for storage. In its present-day form, it records a fluctuating signal by moving the tape across a tape head that polarizes the magnetic domains in the tape in proportion to the audio signal. Tape-recording devices include the reel-to-reel tape deck and the cassette deck, which uses a cassette for storage; the use of magnetic tape for sound recording originated around 1930 in Germany as paper tape with oxide lacquered to it. Prior to the development of magnetic tape, magnetic wire recorders had demonstrated the concept of magnetic recording, but they never offered audio quality comparable to the other recording and broadcast standards of the time; this German invention was the start of a long string of innovations that have led to present day magnetic tape recordings. Magnetic tape revolutionized both music recording industries, it gave artists and producers the power to record and re-record audio with minimal loss in quality as well as edit and rearrange recordings with ease.
The alternative recording technologies of the era, transcription discs and wire recorders, could not provide anywhere near this level of quality and functionality. Since some early refinements improved the fidelity of the reproduced sound, magnetic tape has been the highest quality analog recording medium available; as of the first decade of the 21st century, analog magnetic tape has been replaced by digital recording technologies. The earliest known audio tape recorder was a non-magnetic, non-electric version invented by Alexander Graham Bell's Volta Laboratory and patented in 1886, it employed a 3⁄16-inch-wide strip of wax-covered paper, coated by dipping it in a solution of beeswax and paraffin and had one side scraped clean, with the other side allowed to harden. The machine was of sturdy wood and metal construction, hand-powered by means of a knob fastened to the flywheel; the wax strip passed from one eight-inch reel around the periphery of a pulley mounted above the V-pulleys on the main vertical shaft, where it came in contact with either its recording or playback stylus.
The tape was taken up on the other reel. The sharp recording stylus, actuated by a vibrating mica diaphragm, cut the wax from the strip. In playback mode, a dull, loosely mounted stylus, attached to a rubber diaphragm, carried the reproduced sounds through an ear tube to its listener. Both recording and playback styluses, mounted alternately on the same two posts, could be adjusted vertically so that several recordings could be cut on the same 3⁄16-inch-wide strip. While the machine was never developed commercially, it was an interesting ancestor to the modern magnetic tape recorder which it resembled somewhat in design; the tapes and machine created by Bell's associates, examined at one of the Smithsonian Institution's museums, became brittle, the heavy paper reels warped. The machine's playback head was missing. Otherwise, with some reconditioning, they could be placed into working condition; the waxed tape recording medium was inferior to Edison's wax cylinder medium, Edison's wax cylinder phonograph became the first widespread sound recording technology, used for both entertainment and office dictation.
Franklin C. Goodale adapted movie film for analog audio recording, he received the patent for his invention in 1909. The celluloid film was inscribed and played back with a stylus, in a manner similar to the wax cylinders of Edison's gramophone; the patent description states that the machine could store six records on the same strip of film, side by side, it was possible to switch between them. In 1912, a similar process was used for the Hiller talking clock. In 1932, after six years of developmental work, including a patent application in 1931, Merle Duston, a Detroit radio engineer, created a tape recorder capable of recording both sounds and voice that used a low-cost chemically treated paper tape. During the recording process, the tape moved through a pair of electrodes which imprinted the modulated sound signals as visible black stripes into the paper tape's surface; the sound track could be replayed from the same recorder unit, which contained photoelectric sensors, somewhat similar to the various sound-on-film technologies of the era.
Magnetic recording was conceived as early as 1878 by the American engineer Oberlin Smith and demonstrated in practice in 1898 by Danish engineer Valdemar Poulsen. Analog magnetic wire recording, its successor, magnetic tape recording, involve the use of a magnetizable medium which moves with a constant speed past a recording head. An electrical signal, analogous to the sound, to be recorded, is fed to the recording head, inducing a pattern of magnetization similar to the signal. A playback head can pick up the changes in magnetic field from the tape and convert it into an electrical signal to be amplified and played back through a loudspeaker; the first wire recorder was the Telegraphone invented by Valdemar Poulsen in the late 1890s. Wire recorders for law/office dictation and telephone recording were made continuously by various companies through the 1920s and 1930s; these devices were sold as consumer technologies after World War II. Widespread use of the wire recording device occurred within the decades spanning from 1940 until 1960, following the development of inexpensive designs licensed internationally by the Brush Development Company of Cleveland and the Armour Research Foundation of the Armour Institute of Technology.
These two or