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Philo Farnsworth

Philo Taylor Farnsworth (August 19, 1906 – March 11, 1971) was an American inventor and television pioneer. He made the critical contributions to electronic television that made possible all the video in the world today. He is best known for his 1927 invention of the first fully functional all-electronic image pickup device (video camera tube), the image dissector, as well as the first fully functional and complete all-electronic television system. Farnsworth developed a television system complete with receiver and camera—which he produced commercially through the Farnsworth Television and Radio Corporation from 1938 to 1951, in Fort Wayne, Indiana.

In later life, Farnsworth invented a small nuclear fusion device, the Farnsworth Fusor, employing inertial electrostatic confinement (IEC). Like many fusion devices, it was not a practical device for generating nuclear power, although it provides a viable source of neutrons. The design of this device has been the inspiration for other fusion approaches, including the Polywell reactor concept. Farnsworth held 300 patents, mostly in radio and television.

Early life
Farnsworth was born August 19, 1906, the eldest of five children of Lewis Edwin Farnsworth and Serena Amanda Bastian, a Latter-day Saint couple living in a small log cabin built by Lewis' father in Manderfield, near Beaver, Utah. In 1918, the family moved to a relative's 240 acre ranch near Rigby, Idaho, where his father supplemented his farming income by hauling freight with his horse-drawn wagon. Philo was excited to find that his new home was wired for electricity, with a Delco generator providing power for lighting and farm machinery. He was a quick student in mechanical and electrical technology, repairing the troublesome generator. He found a burned-out electric motor among some items discarded by the previous tenants and rewound the armature; he converted his mother's hand-powered washing machine into an electric-powered one. He developed an early interest in electronics after his first telephone conversation with a distant relative, and he discovered a large cache of technology magazines in the attic of their new home. He won $25 in a pulp-magazine contest for inventing a magnetized car lock. Farnsworth was a member of the Church of Jesus Christ of Latter-day Saints.

Farnsworth excelled in chemistry and physics at Rigby High School. He asked science teacher Justin Tolman for advice about an electronic television system that he was contemplating; he provided the teacher with sketches and diagrams covering several blackboards to show how it might be accomplished electronically, and Tolman encouraged him to develop his ideas. One of the drawings that he did on a blackboard for his chemistry teacher was recalled and reproduced for a patent interference case between Farnsworth and RCA. In 1923, the family moved to Provo, Utah, and Farnsworth attended Brigham Young High School that fall. His father died of pneumonia in January 1924 at age 58, and Farnsworth assumed responsibility for sustaining the family while finishing high school. After graduating BYHS in June 1924, he applied to the United States Naval Academy in Annapolis, Maryland, where he earned the nation's second-highest score on academy recruiting tests. However, he was already thinking ahead to his television projects; he learned that the government would own his patents if he stayed in the military, so he obtained an honorable discharge within months of joining under a provision in which the eldest child in a fatherless family could be excused from military service to provide for his family. He returned to Provo and enrolled at Brigham Young University, but he was not allowed by the faculty to attend their advanced science classes based upon policy considerations. He attended anyway and made use of the university's research labs, and he earned a Junior Radio-Trician certification from the National Radio Institute, and full certification in 1925. While attending college, he met Provo High School student Elma "Pem" Gardner (1908–2006), whom he eventually married.

Farnsworth worked while his sister Agnes took charge of the family home and the second-floor boarding house, with the help of a cousin living with the family. The Farnsworths later moved into half of a duplex, with family friends the Gardners moving into the other side when it became vacant. He developed a close friendship with Pem's brother Cliff Gardner, who shared his interest in electronics, and the two moved to Salt Lake City to start a radio repair business. The business failed, and Gardner returned to Provo.

Farnsworth remained in Salt Lake City and became acquainted with Leslie Gorrell and George Everson, a pair of San Francisco philanthropists who were then conducting a Salt Lake City Community Chest fund-raising campaign. They agreed to fund his early television research with an initial $6,000 in backing, and set up a laboratory in Los Angeles for Farnsworth to carry out his experiments.

Farnsworth married Pem on May 27, 1926, and the two traveled to Berkeley, California, in a Pullman coach. They rented a house at 2910 Derby Street, from which he applied for his first television patent, which was granted on August 26, 1930. By that time they had moved across the bay to San Francisco, where Farnsworth set up his new lab at 202 Green Street.

Career
A few months after arriving in California, Farnsworth was prepared to show his models and drawings to a patent attorney who was nationally recognized as an authority on electrophysics. Everson and Gorrell agreed that Farnsworth should apply for patents for his designs, a decision that proved crucial in later disputes with RCA. Most television systems in use at the time used image scanning devices ("rasterizers") employing rotating "Nipkow disks" comprising a spinning disk with holes arranged in spiral patterns such that they swept across an image in a succession of short arcs while focusing the light they captured on photosensitive elements, thus producing a varying electrical signal corresponding to the variations in light intensity. Farnsworth recognized the limitations of the mechanical systems, and that an all-electronic scanning system could produce a superior image for transmission to a receiving device.

On September 7, 1927, Farnsworth's image dissector camera tube transmitted its first image, a simple straight line, to a receiver in another room of his laboratory at 202 Green Street in San Francisco. Pem Farnsworth recalled in 1985 that her husband broke the stunned silence of his lab assistants by saying, "There you are – electronic television!" The source of the image was a glass slide, backlit by an arc lamp. An extremely bright source was required because of the low light sensitivity of the design. By 1928, Farnsworth had developed the system sufficiently to hold a demonstration for the press. His backers had demanded to know when they would see dollars from the invention; so the first image shown was, appropriately, a dollar sign. In 1929, the design was further improved by elimination of a motor-generator, which meant the television system now had no mechanical parts. That year Farnsworth transmitted the first live human images using his television system, including a three and a half-inch image of his wife Pem.

Many inventors had built electromechanical television systems before Farnsworth's seminal contribution, but Farnsworth designed and built the world's first working all-electronic television system, employing electronic scanning in both the pickup and display devices. He first demonstrated his system to the press on September 3, 1928, and to the public at the Franklin Institute in Philadelphia on August 25, 1934.

In 1930, RCA recruited Vladimir K. Zworykin—who had tried, unsuccessfully, to develop his own all-electronic television system at Westinghouse in Pittsburgh since 1923 —to lead its television development department. Before leaving his old employer, Zworykin visited Farnsworth's laboratory, and was sufficiently impressed with the performance of the Image Dissector that he reportedly had his team at Westinghouse make several copies of the device for experimentation. Zworykin later abandoned research on the Image Dissector, which at the time required extremely bright illumination of its subjects, and turned his attention to what became the Iconoscope. In a 1970s series of videotaped interviews, Zworykin recalled that, "Farnsworth was closer to this thing you're using now [i.e., a video camera] than anybody, because he used the cathode-ray tube for transmission. But, Farnsworth didn't have the mosaic [of discrete light elements], he didn't have storage. Therefore, [picture] definition was very low.... But he was very proud, and he stuck to his method." Contrary to Zworykin's statement, Farnsworth's patent number 2,087,683 for the Image Dissector (filed April 26, 1933) features the "charge storage plate" invented by Tihanyi in 1928 and a "low velocity" method of electron scanning, also describes "discrete particles" whose "potential" is manipulated and "saturated" to varying degrees depending on their velocity. Farnsworth's patent numbers 2,140,695 and 2,233,888 are for a "charge storage dissector" and "charge storage amplifier," respectively.

In 1931, David Sarnoff of RCA offered to buy Farnsworth's patents for $100,000, with the stipulation that he become an employee of RCA, but Farnsworth refused. In June of that year, Farnsworth joined the Philco company and moved to Philadelphia along with his wife and two children. RCA later filed an interference suit against Farnsworth, claiming Zworykin's 1923 patent had priority over Farnsworth's design, despite the fact it could present no evidence that Zworykin had actually produced a functioning transmitter tube before 1931. Farnsworth had lost two interference claims to Zworykin in 1928, but this time he prevailed and the U.S. Patent Office rendered a decision in 1934 awarding priority of the invention of the image dissector to Farnsworth. RCA lost a subsequent appeal, but litigation over a variety of issues continued for several years before Sarnoff finally agreed to pay Farnsworth royalties.

In 1932, while in England to raise money for his legal battles with RCA, Farnsworth met with John Logie Baird, a Scottish inventor who had given the world's first public demonstration of a working television system in London in 1926, using an electro-mechanical imaging system, and who was seeking to develop electronic television receivers. Baird demonstrated his mechanical system for Farnsworth.

In May 1933, Philco severed its relationship with Farnsworth because, said Everson, "it [had] become apparent that Philo's aim at establishing a broad patent structure through research [was] not identical with the production program of Philco." In Everson's view the decision was mutual and amicable. Farnsworth set up shop at 127 East Mermaid Lane in Philadelphia, and in 1934 held the first public exhibition of his device at the Franklin Institute in that city.

After sailing to Europe in 1934, Farnsworth secured an agreement with Goerz-Bosch-Fernseh in Germany. Some image dissector cameras were used to broadcast the 1936 Olympic Games in Berlin.

Farnsworth returned to his laboratory, and by 1936 his company was regularly transmitting entertainment programs on an experimental basis. That same year, while working with University of Pennsylvania biologists, Farnsworth developed a process to sterilize milk using radio waves. He also invented a fog-penetrating beam for ships and airplanes.

In 1936, he attracted the attention of Collier's Weekly, which described his work in glowing terms. "One of those amazing facts of modern life that just don't seem possible—namely, electrically scanned television that seems destined to reach your home next year, was largely given to the world by a nineteen-year-old boy from Utah ... Today, barely thirty years old he is setting the specialized world of science on its ears."

In 1938, Farnsworth established the Farnsworth Television and Radio Corporation in Fort Wayne, Indiana, with E. A. Nicholas as president and himself as director of research. In September 1939, after a more than decade-long legal battle, RCA finally conceded to a multi-year licensing agreement concerning Farnsworth's 1927 patent for television totaling $1 million. RCA was then free, after showcasing electronic television at New York World's Fair on April 20, 1939, to sell electronic television cameras to the public.

Farnsworth Television and Radio Corporation was purchased by International Telephone and Telegraph (ITT) in 1951. During his time at ITT, Farnsworth worked in a basement laboratory known as "the cave" on Pontiac Street in Fort Wayne. From there, he introduced a number of breakthrough concepts, including a defense early warning signal, submarine detection devices, radar calibration equipment and an infrared telescope. "Philo was a very deep person—tough to engage in conversation, because he was always thinking about what he could do next", said Art Resler, an ITT photographer who documented Farnsworth's work in pictures. One of Farnsworth's most significant contributions at ITT was the PPI Projector, an enhancement on the iconic "circular sweep" radar display, which allowed safe air traffic control from the ground. This system developed in the 1950s was the forerunner of today's air traffic control systems.

In addition to his electronics research, ITT management agreed to nominally fund Farnsworth's nuclear fusion research. He and staff members invented and refined a series of fusion reaction tubes called "fusors". For scientific reasons unknown to Farnsworth and his staff, the necessary reactions lasted no longer than thirty seconds. In December 1965, ITT came under pressure from its board of directors to terminate the expensive project and sell the Farnsworth subsidiary. It was only due to the urging of president Harold Geneen that the 1966 budget was accepted, extending ITT's fusion research for an additional year. The stress associated with this managerial ultimatum, however, caused Farnsworth to suffer a relapse. A year later he was terminated and eventually allowed medical retirement.

In 1967, Farnsworth and his family moved back to Utah to continue his fusion research at Brigham Young University, which presented him with an honorary doctorate. The university also offered him office space and an underground concrete bunker for the project. Realizing ITT would dismantle its fusion lab, Farnsworth invited staff members to accompany him to Salt Lake City, as team members in Philo T. Farnsworth Associates (PTFA). By late 1968, the associates began holding regular business meetings and PTFA was underway. They promptly secured a contract with the National Aeronautics and Space Administration (NASA), and more possibilities were within reach—but financing stalled for the $24,000 a month required for salaries and equipment rental.

In a 1996 videotaped interview by the Academy of Television Arts & Sciences, Farnsworth's wife recounted his change of heart about the value of television, after seeing Neil Armstrong becoming the first person to walk on the Moon in real time on July 20, 1969, along with millions of others: "We were watching it, and, when Neil Armstrong landed on the moon, Phil turned to me and said, 'Pem, this has made it all worthwhile.' Before then, he wasn't too sure."

By Christmas 1970, PTFA had failed to secure the necessary financing, and the Farnsworths had sold all their own ITT stock and cashed in Philo's life insurance policy to maintain organizational stability. The underwriter had failed to provide the financial backing that was to have supported the organization during its critical first year. The banks called in all outstanding loans, repossession notices were placed on anything not previously sold, and the Internal Revenue Service put a lock on the laboratory door until delinquent taxes were paid. In January 1971, PTFA disbanded.

Farnsworth had begun abusing alcohol in his later years, and as a result became seriously ill with pneumonia, and died on March 11, 1971, at his home in Holladay, Utah.

Farnsworth's wife Elma Gardner "Pem" Farnsworth fought for decades after his death to assure his place in history. Farnsworth always gave her equal credit for creating television, saying, "my wife and I started this TV." She died on April 27, 2006, at age 98. The inventor and wife were survived by two sons, Russell (then living in New York City), and Kent (then living in Fort Wayne, Indiana).

In 1999, Time magazine included Farnsworth in the "Time 100: The Most Important People of the Century".

Electronic TV
Farnsworth worked out the principle of the image dissector in the summer of 1921, not long before his 15th birthday, and demonstrated the first working version on September 7, 1927, having turned 21 the previous August. A farm boy, his inspiration for scanning an image as a series of lines came from the back-and-forth motion used to plow a field. In the course of a patent interference suit brought by the Radio Corporation of America in 1934 and decided in February 1935, his high school chemistry teacher, Justin Tolman, produced a sketch he had made of a blackboard drawing Farnsworth had shown him in spring 1922. Farnsworth won the suit; RCA appealed the decision in 1936 and lost. Farnsworth received royalties from RCA, but he never became wealthy. The video camera tube that evolved from the combined work of Farnsworth, Zworykin, and many others was used in all television cameras until the late 20th century, when alternate technologies such as charge-coupled devices began to appear.

Farnsworth also developed the "image oscillite", a cathode ray tube that displayed the images captured by the image dissector.

Farnsworth called his device an image dissector because it converted individual elements of the image into electricity one at a time. He replaced the spinning disks with cesium, an element that emits electrons when exposed to light.

In 1984, Farnsworth was inducted into the National Inventors Hall of Fame.

Fusor
The Farnsworth fusor is an apparatus designed by Farnsworth to create nuclear fusion. Unlike most controlled fusion systems, which slowly heat a magnetically confined plasma, the fusor injects high-temperature ions directly into a reaction chamber, thereby avoiding a considerable amount of complexity.

When the Farnsworth fusor was first introduced to the fusion research world in the late 1960s, the fusor was the first device that could clearly demonstrate it was producing fusion reactions at all. Hopes at the time were high that it could be quickly developed into a practical power source. However, as with other fusion experiments, development into a power source has proven difficult. Nevertheless, the fusor has since become a practical neutron source and is produced commercially for this role.

Other inventions
At the time he died, Farnsworth held 300 U.S. and foreign patents. His inventions contributed to the development of radar, infra-red night vision devices, the electron microscope, the baby incubator, the gastroscope, and the astronomical telescope.

TV appearance
Although he was the man responsible for its technology, Farnsworth appeared only once on a television program. On July 3, 1957, he was a mystery guest ("Doctor X") on the CBS quiz show I've Got A Secret. He fielded questions from the panel as they unsuccessfully tried to guess his secret ("I invented electronic television."). For stumping the panel, he received $80 and a carton of Winston cigarettes. Host Garry Moore then spent a few minutes discussing with Farnsworth his research on such projects as an early analog high-definition television system, flat-screen receivers, and fusion power. Farnsworth said, "There had been attempts to devise a television system using mechanical disks and rotating mirrors and vibrating mirrors—all mechanical. My contribution was to take out the moving parts and make the thing entirely electronic, and that was the concept that I had when I was just a freshman in high school in the Spring of 1921 at age 14."

A letter to the editor of the Idaho Falls Post Register disputed that Farnsworth had made only one television appearance. Roy Southwick claimed "... I interviewed Mr. [Philo] Farnsworth back in 1953—the first day KID-TV went on the air." KID-TV, which later became KIDK-TV, was then located near the Rigby area where Farnsworth grew up.

Honors

 * In 1967, Farnsworth was issued an honorary degree by Brigham Young University, which he had briefly attended after graduating from Brigham Young High School.
 * In 2006, Farnsworth was posthumously presented the Eagle Scout award when it was discovered he had earned it but had never been presented with it. The award was presented to his wife, Pem, who died four months later.
 * Farnsworth was posthumously inducted into the Broadcast Pioneers of Philadelphia Hall of Fame in 2006.
 * He was inducted into the Television Academy Hall of Fame in 2013.
 * He is recognized in the Hall of Fame of the Indiana Broadcast Pioneers—which notes that, in addition to his inventive accomplishments, his company owned and operated WGL radio in Fort Wayne, Indiana.

Memorials

 * A bronze statue of Farnsworth represents Utah in the National Statuary Hall Collection, located in the U.S. Capitol building. On January 28, 2018, amid extended debate and over sizable public objection, the Utah Legislature voted to replace it with one of Martha Hughes Cannon.
 * Another statue sits inside the Utah State Capitol, in Salt Lake City.
 * A Pennsylvania Historical and Museum Commission marker located at 1260 E. Mermaid Lane, Wyndmoor, Pennsylvania, commemorates Farnsworth's television work there in the 1930s. The Plaque reads "Inventor of electronic television, he led some of the first experiments in live local TV broadcasting in the late 1930s from his station W3XPF located on this site. A pioneer in electronics, Farnsworth held many patents and was inducted into the Inventors Hall of Fame."
 * On September 15, 1981, a plaque honoring Farnsworth as The Genius of Green Street was placed on the 202 Green Street location (37.80037°N, -122.40251°W) of his research laboratory in San Francisco by the California State Department of Parks and recreation.
 * In October 2008, the Letterman Digital Arts Center in San Francisco installed a statue of Farnsworth sculpted by Lawrence Noble in front of its D building.
 * A plaque honoring Farnsworth is located next to his former home at 734 E. State Blvd, in a historical district on the southwest corner of E. State and St. Joseph Blvds in Fort Wayne, Indiana.
 * Farnsworth is one of the inventors honored with a plaque in the Walt Disney World's "Inventor's Circle" in Future World West in EPCOT.
 * A 1983 United States postage stamp honored Farnsworth.
 * On January 10, 2011, Farnsworth was inducted by Mayor Gavin Newsom into the newly established San Francisco Hall of Fame, in the science and technology category.
 * Farnsworth's television-related work, including an original TV tube he developed, are on display at the Farnsworth TV & Pioneer Museum in Rigby, Idaho.

Things named after Farnsworth

 * The Philo T. Farnsworth Award is one of the Primetime Engineering Emmy Awards given to honor companies and organizations that have significantly affected the state of television and broadcast engineering over a long period of time.
 * The Philo Awards (officially Philo T. Farnsworth Awards, not to be confused with the one above) is an annual public-access television cable TV competition within the Ohio, Indiana, Kentucky, and Michigan region, where the winners receive notice for their efforts in various categories in producing community media.
 * Philo, a streaming television provider based in San Francisco where his lab was located, is named for Farnsworth.
 * Farnsworth Peak on the northern end of the Oquirrh Mountains, approximately 18 miles (29 km) south west of Salt Lake City, Utah, is the location of many of the area's television and FM radio transmitters.
 * The scenic "Farnsworth Steps" in San Francisco lead from Willard Street (just above Parnassus) up to Edgewood Avenue.
 * Several buildings and streets around rural Brownfield, Maine are named for Farnsworth as he lived there for some time.
 * The Philo T. Farnsworth Elementary School of the Jefferson Joint School District in Rigby, Idaho (later becoming a middle school) is named in his honor.
 * While Philo T. Farnsworth Elementary School in the Granite School District in West Valley City, Utah is named after his cousin by the same name who was a former school district administrator.

In popular culture

 * In "Cliff Gardner", the October 19, 1999 episode of the second season of Aaron Sorkin's television comedy Sports Night, William H. Macy's character, Sam, delivers an extended monologue recounting Farnsworth's invention of television and the assistance provided to him by Cliff Gardner.{{fact|date=July 2022}
 * The eccentric broadcast engineer in the 1989 film UHF is named Philo in tribute to Farnsworth.
 * In "Levers, Beakmania, & Television", the November 14, 1992 season 1 episode of Beakman's World, Paul Zaloom appears as the "guest scientist" Philo T. Farnsworth explaining his most notable invention.
 * A fictionalized representation of Farnsworth appears in Canadian writer Wayne Johnston's 1994 novel, Human Amusements. The main character in the novel appears as the protagonist in a television show that features Farnsworth as the main character.  In the show, an adolescent Farnsworth invents many different devices (television among them) while being challenged at every turn by a rival inventor.
 * The Futurama character Professor Farnsworth, who first appeared in 1999, is named after and partially inspired by Philo Farnsworth, and in the episode "All the Presidents' Heads" was revealed to have descended from him.
 * Farnsworth and the introduction of television are significant plot elements in Carter Beats the Devil, a novel by Glen David Gold published in 2001 by Hyperion.
 * The Farnsworth Invention, a stage play by Aaron Sorkin that debuted in 2007 after Sorkin adapted it from his unproduced screenplay, dramatized the conflict arising from Farnsworth's invention of TV and the alleged stealing of the design by David Sarnoff of RCA.
 * The 2009 SyFy television series Warehouse 13 features a video communicator called "The Farnsworth." In the show's universe, this was designed by Philo Farnsworth.
 * In the video game Trenched, renamed as Iron Brigade, the main antagonist is a character named Vladimir Farnsworth, who created mechanical enemies known as "Tubes" that spread a deadly broadcast. This character name alludes to Philo Farnsworth and Vladimir K. Zworykin, who invented the iconoscope.
 * The 2009 animated film Cloudy with a Chance of Meatballs features an amateur inventor named Flint Lockwood, who idolizes notable inventors. On his bedroom walls are the images of Thomas Edison and Philo Farnsworth, among others.

Fort Wayne sites

In 2010, the former Farnsworth factory in Fort Wayne, Indiana, was razed, eliminating the "cave," where many of Farnsworth's inventions were first created, and where its radio and television receivers and transmitters, television tubes, and radio-phonographs were mass-produced under the Farnsworth, Capehart, and Panamuse trade names. The facility was located at 3702 E. Pontiac St.

Also that year, additional Farnsworth factory artifacts were added to the Fort Wayne History Center's collection, including a radio-phonograph and three table-top radios from the 1940s, as well as advertising and product materials from the 1930s to the 1950s.

Farnsworth's Fort Wayne residence from 1948 to 1967, then the former Philo T. Farnsworth Television Museum, stands at 734 E. State Blvd, on the southwest corner of E. State and St. Joseph Blvds. The residence is recognized by an Indiana state historical marker and was listed on the National Register of Historic Places in 2013.

Marion, Indiana factory
In addition to Fort Wayne, Farnsworth operated a factory in Marion, Indiana, that made shortwave radios used by American combat soldiers in World War II. Acquired by RCA after the war, the facility was located at 3301 S. Adams St.

Patents

 * U.S. Patent 1,773,980 : Television system (filed January 7, 1927, issued August 26, 1930)
 * : Television receiving system (filed January 7, 1927, issued August 26, 1930)
 * : Electric oscillator system (filed January 7, 1927, issued May 13, 1930)
 * : Light valve (filed January 7, 1927, issued May 26, 1931)
 * : Television method (filed January 9, 1928, issued August 8, 1939)
 * : Photoelectric apparatus (filed January 9, 1928, issued August 14, 1934)
 * : Television scanning and synchronization system (filed May 5, 1930, issued June 24, 1941)
 * : Dissector target (filed July 7, 1930, issued December 26, 1933)
 * : Projecting oscillight (filed July 14, 1931, issued December 13, 1938)
 * : Scanning oscillator (filed April 3, 1933, issued November 3, 1936)
 * : Image dissector (filed April 26, 1933, issued July 20, 1937)
 * : Oscillation generator (filed July 5, 1934, issued February 23, 1937)
 * : Projection means (filed November 6, 1934, issued January 10, 1939)
 * : Image projector (filed February 6, 1935, issued March 4, 1941)
 * : Means of electron multipaction (filed March 12, 1935, issued January 10, 1939)
 * : Oscillator (filed March 12, 1935, issued September 26, 1939)
 * : Amplifier (filed March 12, 1935, issued November 12, 1940)
 * : Means for producing incandescent images (filed May 7, 1935, issued April 25, 1939)
 * : Charge storage dissector (filed July 6, 1935, issued December 20, 1938)
 * : Cathode ray amplifier (filed July 6, 1935, issued January 14, 1941)
 * : Charge storage amplifier (filed July 6, 1935, issued March 4, 1941)
 * : Cathode ray amplifying tube (filed August 10, 1935, issued July 29, 1941)
 * : Charge storage tube (filed September 14, 1935, issued November 30, 1937)
 * : Multipactor oscillator (filed January 27, 1936, issued November 22, 1938)
 * : Scanning current generator (filed February 10, 1936, issued September 10, 1940)
 * U.S. Patent 2,089,054 : Incandescent light source (filed March 9, 1936, issued August 3, 1937)
 * : Absorption oscillator (filed March 9, 1936, issued May 23, 1939)
 * : Secondary emission electrode (filed March 24, 1936, issued December 13, 1938)
 * : Means and method for producing electronic multiplication (filed May 16, 1936, issued June 11, 1940)
 * : Means and method of controlling electron multipliers (filed May 16, 1936, issued December 20, 1938)
 * : Electron multiplier (filed May 18, 1936, issued October 28, 1941)
 * U.S. Patent 2,141,837 : Multistage multipactor (filed June 1, 1936, issued December 27, 1938)
 * : Image dissector (filed August 18, 1936, issued October 1, 1940)
 * : Means and method of operating electron multipliers (filed August 18, 1936, issued August 30, 1938)
 * : Repeater (filed October 31, 1936, issued January 10, 1939)
 * : Cathode ray tube (filed November 2, 1936, issued December 13, 1938)
 * : High power projection oscillograph (filed November 2, 1936, issued February 22, 1938)
 * : Cold cathode electron discharge tube (filed November 4, 1936, issued December 26, 1939)
 * : Electron multiplier (filed November 9, 1936, issued November 14, 1939)
 * : X-ray projection device
 * : Cold cathode electron discharge tube
 * : Electric discharge device for producing interaction between nuclei
 * : Method and apparatus for producing nuclear fusion reactions
 * : Electrostatic containment in fusion reactors

title: Philo Farnsworth


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Adjustable spanner

An adjustable spanner (UK and most other English-speaking countries), shifting spanner (Australia and New Zealand), English wrench (Turkey) or adjustable wrench (US and Canada) is any of various styles of spanner (wrench) with a movable jaw, allowing it to be used with different sizes of fastener head (nut, bolt, etc.) rather than just one fastener size, as with a conventional fixed spanner.

Forms and names
There are many forms of adjustable spanners; many of them are screw-adjusted, whereas others use levers, and some early ones used wedges. The early taper-locking spanners needed a hammer to set the movable jaw to the size of the nut. The modern screw-adjusted spanner and lever types are easily and quickly adjusted. Some adjustable spanners automatically adjust to the size of the nut, using a motor and battery. Simpler models use a serrated edge to lock the movable jaw to size, while more sophisticated versions are digital types that use sheets or feelers to set the size.

Geesin (2015) shows that wrenches with screw adjustment of various kinds were well known in the early 19th century and that one by William Barlow in 1808 was prescient. By the 1830s, many designs with a central screw and a lower jaw moved by a nut were well known. Geesin and others  document that English engineers Richard Clyburn and Edwin Beard Budding presented some influential new designs in 1842 and 1843. The one by Clyburn had the form of thumbwheel screw with worm-on-rack arrangement that would later be the most famous via subsequent adaptations. Improvements followed. In 1885 Enoch Harris received US patent 326868 for his spanner that permitted both the jaw width and the angle of the handles to be adjusted and locked.

One of the most widely known forms of adjustable wrench in the 21st century is an improved version of the Clyburn type; it was developed in 1891–1892. The Swedish company Bahco attributes its invention to Johan Petter Johansson, who in 1892 received a Swedish patent for it. In Canada and the United States, this type is often known as a Crescent wrench owing to widespread genericization of the brand name of the company that held the original 1915 U.S. patent for this type, the Crescent Tool Company. (The Crescent brand is now owned by the Apex Tool Group). As Geesin 2015 documents, the worm-on-rack type (regardless of which terminology is used to name it) was invented in Britain, and later popularized in Scandinavia via the Bahco/Johansson improvement, before its manufacture in the United States was patented. The Bahco/Johansson/Crescent category (regardless of which terminology is used to name it) became so dominant in the 20th century that in North America, the very term adjustable wrench usually elicits the meaning of this type in general usage today, unless another type is specified. In Australia it is sometimes referred to as a "shifting spanner" or its abbreviated form of "shifter".

Monkey wrenches are another type of adjustable spanner with a long history; the origin of the name is not entirely clear, but Geesin reports that it originated in Britain with a fancied resemblance of the wrench's jaws to that of a monkey's face, and that the many convoluted folk etymologies that later developed were baseless. Before the Bahco/Johansson/Crescent type became widespread in the United States, during the industrial era of the 1860s to the 1910s, various monkey wrench types were the dominant form of adjustable wrench there.

Another popular type of adjustable spanner has a base and jaws that form four sides of a hexagon, and is therefore particularly suited for hexagonal nuts ("hex nuts") and hexagonal headed ("hex head") cap screws and bolts.

In some parts of Europe, adjustable spanners are often called a Bahco, owing to genericization of the name of the Bahco/Johansson type. In Denmark, this type of spanner is commonly referred to as a "svensknøgle", which basically translates to Swedish key. The Swedes themselves call the key "skiftnyckel", which is translated into adjustable key (shifting key). In Australia, adjustable spanners are also referred to as "shifters". In Spain, this kind of spanner is commonly called "llave inglesa", which means literally English key. Remarking the difference with the pipe wrench, also adjustable, in Spain this one is called "grifa", and it does not have any accurate translation.

Design and use
The fixed jaw can withstand bending stress far better than can the movable jaw, because the latter is supported only by the flat surfaces on either side of the guide slot, not the full thickness of the tool. The tool is therefore usually angled so that the movable jaw's area of contact is closer to the body of the tool, which means less bending stress. Still, one should avoid applying excessive force on tight bolts, since doing so can pry open the mounting of the movable jaw causing the wrench to no longer be able to be snugged to bolt heads, loosen too easily, or mar bolt heads. In some cases the jaws of the tool can break.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Adjustable spanner


text:
Walvis Bay

Walvis Bay (lit. Whale Bay; Walvisbaai; ) is a city in Namibia and the name of the bay on which it lies. It is the second largest city in Namibia and the largest coastal city in the country. The city covers an area of 29 km2 of land. The bay is a safe haven for sea vessels because of its natural deep-water harbour, protected by the Pelican Point sand spit, being the only natural harbour of any size along the country's coast. Being rich in plankton and marine life, these waters also draw large numbers of southern right whales, attracting whalers and fishing vessels.

A succession of colonists developed the location and resources of this strategic harbour settlement. The harbour's value in relation to the sea route around the Cape of Good Hope had caught the attention of world powers since it was discovered by the outside world in 1485. The importance of the harbour, combined with its extreme isolation by land, explains the complicated political history of the town. For much of its history, Walvis Bay was governed as an exclave separate from the rest of the territory that today is Namibia.

The town is situated just north of the Tropic of Capricorn in the Kuiseb River delta and lies at the end of the TransNamib Railway to Windhoek, and on B2 road.

Walvis Bay, with its large bay and sand dunes, is an important centre of tourism activity in Namibia. Attractions include the artificial Bird Island, centre of a guano collection industry, the Dune 7 sand dune, the salt works, the abundant birdlife, and a museum. Kuisebmund Stadium, home to two clubs in the Namibia Premier League, is also located in the city. The beach resort of Langstrand lies just a few kilometres north. The Walvis Bay Export Processing Zone is an important facet of the local economy.

Etymology
The Dutch referred to it as Walvisch Baye and the English as Whale Bay. In its eventual formal incorporation, it was named Walfish Bay, which was changed to Walvish Bay, and ultimately to Walvis Bay. It has also been referred to as Walwich Bay or Walwisch Bay. The Herero people of the area called it Ezorongondo.

History
Portuguese navigator Diogo Cão reached Cape Cross, north of the bay, in 1485. There followed Bartolomeu Dias, who anchored his flagship São Cristóvão in what is now Walvis Bay on 8 December 1487, on his expedition to discover a sea route to the East via the Cape of Good Hope. He named the bay "O Golfo de Santa Maria da Conceição". However, the Portuguese did not formally stake a claim to Walvis Bay.

Walvis Bay was founded at the end of the 18th century as a stopover for sea travel between Cape Town and the Netherlands by the Dutch East India Company. No permanent (year round) settlement was attempted and little commercial development occurred on the site until the late 19th century. In the meantime, the Cape Colony had become British, and during the Scramble for Africa, the British claimed Walvis Bay. They permitted the Cape Colony to complete the annexation of the territory in 1884, together with the Penguin Islands, following initial steps which had been taken in 1878.

In 1910, Walvis Bay, as part of the Cape Colony, became part of the newly formed Union of South Africa. Subsequently, a dispute arose with Germany over the exclave's boundaries, which was eventually settled in 1911, with Walvis Bay being allocated an area of 434 sqmi. The exclave was overrun by the Germans during the South West Africa Campaign early in the First World War, but the Union Defence Force (UDF) of South Africa eventually ousted the Germans in 1915. Subsequently, Walvis Bay was quickly integrated into the new martial law regime in South West Africa.

South Africa was later awarded control (a Class "C" mandate) over South West Africa by the League of Nations to administer the territory. Civilian rule was restored in South West Africa in 1921 and administration of Walvis Bay was transferred to South West Africa under the South West Africa Affairs Act of 1922.

Despite the territory never having been part of German South West Africa, the Act stated that: "the port and settlement of Walvis Bay, which forms part of the Cape of Good Hope, shall for judicial and administrative purposes be regarded as if it were part of the mandated territory of South West Africa". However, South Africa had also sought to annex South West Africa itself, and had presented such a proposal to the League of Nations. Consequently, in 1949, the Act was amended to give representation in the Parliament of South Africa to whites in South West Africa.

In 1971, on December 14 the Namibian general contract workers strike began in Walvis Bay, after starting the day before in Windhoek. The goal of the strike was the abolition of the contract labour system, to oppose apartheid, and promote Namibia's independence.

In 1977, following increasing international pressure to relinquish its control over South West Africa, South Africa repealed the Act, but transferred control of Walvis Bay back to the Cape Province, thereby making it an exclave. From 1980, it was represented in both the Provincial Council and the House of Assembly as part of the Green Point constituency in Cape Town, before becoming a separate constituency in 1982.

In response, the United Nations Security Council passed Resolution 432 (1978), which declared that "the territorial integrity and unity of Namibia must be assured through the reintegration of Walvis Bay within its territory".

In 1990, South West Africa gained independence as Namibia, but Walvis Bay remained under South African sovereignty, with South Africa increasing the number of troops. However, in 1992, the two countries agreed to establish a transitional Joint Administrative Authority for Walvis Bay and the Offshore Islands. The Authority was headed by two Chief Executive Officers, Nangolo Mbumba, then Secretary to the Namibian Cabinet, and Carl von Hirschberg, former South African Ambassador to the United Nations.

In August 1993, prior to the end of apartheid, the Multiparty Negotiating Forum in South Africa passed a resolution calling for "the incorporation-reintegration of Walvis Bay and the Off-Shore Islands into Namibia." The Transfer of Walvis Bay to Namibia Act was passed by the Parliament of South Africa that year. Following the signing of a treaty between the two countries, South Africa formally transferred sovereignty of Walvis Bay and the Penguin Islands to Namibia on 1 March 1994.

Suburbs
Due to its South African administration Walvis Bay was developed as a segregated town. The suburb of Kuisebmond, located 3.2 kilometres (1.8 mi) from Walvis Bay city centre, housed Black people; Narraville, located 3.3 kilometres (2 mi) from Walvis Bay city centre, was inhabited by Coloureds; and Whites lived in the city centre.

After the incorporation of the town into Namibia, many people have settled in shacks around it. In an effort to reduce the impact of the informal settlements, the municipality formed the Tutaleni Housing Project to the northeast.

Climate
Despite its location within the tropics, Walvis Bay features the very rare mild variation of the cold desert climate (BWk) according to the Köppen climate classification. It is caused by the rain shadow of the Naukluft Mountains and the cooling effect of the coastal sea temperature by the Benguela Current. Walvis Bay receives only 13.2 mm average precipitation per year, making it one of the driest cities on earth. Despite its dry climate, the city is relatively humid. Average relative humidity throughout the year remains above 80%. The warmest month is February with average temperature 17.9 C, while the coolest months are August and September with average temperature 13.2 C. The diurnal temperature range is also low, averaging only 5.7 C-change.

A weather station operated on the Pelican Point headland from 1958 to 1984. Unusually, the highest temperatures are not recorded during the summer; autumn, spring, and even winter have all seen higher temperatures than the hottest days in summer. These record highs occur when offshore winds blow downwards from the high plateau inland and are nonetheless mild by comparison to many other cities in the tropics at the same latitude. Higher temperatures have been recorded, even just slightly inland, such as a report of 42.8 C at the airport on April 15, 2016.

Tourism
Tourism has had an increasing influence in the town's economy, with international tourists arriving at its airport and port facilities. Several cruise liners visit the port each year. With many tourism activities hosted by small and large tour operators the town has turned into a tourism destination.

Fishing
In Walvis Bay there are a variety of fishing companies like Hangana Seafood, Caroline Fishing, Benguella Fishing Company, Cadilu Fishing, Etosha Fisheries, Kuiseb Fishing Enterprises, Blue Ocean Products, Benguella Sea Products, Consortium Fisheries, Talanam Fish Processor. These companies catch diverse types of fish, like snoek, horse mackerel, anchovy, white steenbras, kabeljou, kingklip, hake, catfish, tuna, and sardines. Hangana Seafood are processors and exporters of fish and fish products. As such, the fishing enterprise accounts for a major part of Walvis Bay's economy.

In May 2018, a spokesman for the National Fishing Corporation of Namibia (Fishcor), confirmed that a new N$530 million onshore processing plant would be operational by September 2018. After completion, the factory (which plans to employ 700 people of which 70% will be female), promises to be the largest pelagic processing plant in sub-Saharan Africa and will process about 80 000 tonnes of fish per annum.

Manufacturing
In March 2018 the Namibian government in association with French Groupe PSA signed an investment agreement to initiate a joint-venture to assemble Opel and Peugeot vehicles in Walvis Bay. The N$190m-project has been earmarked to commence in 2018 with a forecasted annual target volume of 5000 units by 2020, a target carried by SACU countries' market demand. However, Peugeot threatened to close the plant over disputes with South Africa over import tariffs.

Walvis Bay Salt produces approximately 1 million tons of salt per year through solar evaporation of sea water. Most of the salt is for industrial use but the company also produces table salt under the "Cerebos" brand.

Transport

Walvis Bay is an important logistical port for the southern African region, providing port facilities for the import and export of cargo for the rest of Namibia, Zambia, Democratic Republic of Congo, and Botswana. Since the Walvis Bay Corridor Group (WBCG) was established in 2000, cargo moving through the port has increased from 30,000 containers a year to 370,000 containers in 2016. As of 2017 the port was being upgraded to increase its capacity to move 1 million containers a year by 2019. Bureaucratic and logistical problems at the city's competitor port at Durban, South Africa have diverted traffic to the port at Walvis Bay. Ninety-five percent of all cargo hauled overland through Walvis Bay is carried by truck.

The Walvis Bay Corridor Group is gearing up to increase import/export-business opportunities in Namibia. The Namibian National Development Plan expects to complete the expansion programme of the Walvis Bay port by 2019. Because of the harbour's geographical positioning, authorities plan to gain a footprint in providing landlocked Southern African Development Community (SADC) countries with a vital logistical hub. In addition to the importance of the port, development would strengthen trade corridors which consists of current road and rail networks.

In an attempt to strengthen and enhance trade relations between other African countries, Namport (the Namibian Port Authority) in April 2019 signed a five-year MoU (Memorandum of Understanding) with the Port Authority of Dakar, Senegal.

Walvis Bay International Airport provides commercial flight services to the city's residents, as well as to neighbouring towns and villages. Airlink services flights between South Africa and Walvis Bay.

In August 2019 a new container terminal was opened, built on a 40-acre platform reclaimed from the sea. The terminal was built by the state-owned China Harbour Engineering Company with funds from the Namibian government and the African Development Bank, costing N$4.2b.

This increases the capacity of the port to 750,000 containers per year from 350,000. The terminal also includes a dedicated cruise liner berth.

Education
Walvis Bay has a number of public (government-run), semi-public, and private schools. Among them are Duneside High School, Duinesig Primary School, International School of Walvis Bay, The Dolphin Schools, Alexanders Private School, Kuisebmond Secondary School, Walvis Bay Private School and others. A number of kindergartens cater to young children.

The Namibian Maritime and Fisheries Institute (NAMFI) is a tertiary education institution based in town. International University of Management (IUM), Welwitchia Health Training Center and Monitronics Success College both have branches in Walvis Bay.

Politics
Walvis Bay is governed by a municipal council that has ten seats.

Election results
The 2015 local authority election was won by the SWAPO party which gained eight seats (5,818 votes). One seat each was won by the Democratic Turnhalle Alliance (DTA, 565 votes) and the United Democratic Front (UDF, 433 votes).

The 2020 local authority election was won by the Independent Patriots for Change (IPC), an opposition party formed in August 2020. The IPC obtained 5,043 votes and gained four seats. SWAPO was the runner-up, obtaining 3,348 votes and gaining three seats. One seat each went to the Landless People's Movement (LPM, a new party registered in 2018, 1,207 votes), the local Joint Walvis Bay Residents Association with 945 votes, and the Popular Democratic Movement (PDM, the new name of the DTA) with 658 votes.

Twin towns – sister cities
Walvis Bay is twinned with:

 * Lobatse in Botswana
 * Drakenstein in South Africa
 * 🇳🇴 Kristiansand in Norway.

Notable people

 * Neshani Andreas (1964–2011), a writer, she also worked as a teacher and for the American Peace Corps.
 * Niko Bessinger (1948–2008), politician and independence activist.
 * Otto Herrigel (1937–2013), businessman and politician; first Minister of Finance, 1990 and 1992.
 * Derek Klazen (born 1965), politician and former mayor of Walvis Bay, minister of fisheries and marine resources
 * Uilika Nambahu, politician, mayor of Walvis Bay in 2008
 * Top Cheri (born 1991), singer and entrepreneur.
 * Omar van Reenen, LGBT activist, junior mayor of Walvis from 2014 to 2015, and served as Vice President of The State University of New York Student Assembly from 2020 to 2021

Sport

 * Johanna Benson (born 1990), Paralympic gold medalist in the T37 long jump
 * Chrysander Botha (born 1988), rugby union player with 55 caps for Namibia
 * twins Shalako & Zhivago Groenewald (born 1993), former first-class cricketers.
 * Percy Montgomery (born 1974), former rugby player, with 102 caps with South Africa.
 * Harry Simon (born 1971), former professional boxer.
 * Hendrik Somaeb (born 1992), footballer with 30 caps for Namibia
 * Damian Stevens (born 1995), rugby union player with 25 caps for Namibia
 * Marius Visser (born 1982), rugby union player with 18 caps for Namibia

Sports
Walvis Bay contains open spaces, scenic beauty and unique marine and plant life. It is well suited for the outdoor lifestyle, boasting sports such as sandboarding, kiting, surfing, swimming, angling, sailing, golf and other indoor and outdoor sport codes. There is Walvis Bay Lagoon and Aquatic Activities, Kuiseb River Delta and the beach itself where people enjoy swimming and catching fish.

The 2 km sand spit allows the adjacent water to remain smooth in very strong winds, ideal for record attempting vessels like that by the Vestas Sailrocket. The ocean side of the sand spit has a world-famous surf spot known in the international surf media as "Skeleton Bay."

The city is home to Eleven Arrows F.C. and Blue Waters F.C., football clubs that compete in the Namibia Premier Football League, and the Sparta Cricket Club Ground.

Places of worship
Among the places of worship, they are predominantly Christian churches and temples: Evangelical Lutheran Church in Namibia (Lutheran World Federation), Evangelical Lutheran Church in the Republic of Namibia (Lutheran World Federation), Baptist Convention of Namibia (Baptist World Alliance), Assemblies of God, Catholic Church. In addition to that there are also Anglican Churches namely St Raphael Anglican Church in Mondesa, St Mathews Anglican Church close to Namport as well as Seafarers Mission at Namport. There is also a Muslim mosque.

title: Walvis Bay


text:
Viscometer

A viscometer (also called viscosimeter) is an instrument used to measure the viscosity of a fluid. For liquids with viscosities which vary with flow conditions, an instrument called a rheometer is used. Thus, a rheometer can be considered as a special type of viscometer. Viscometers can measure only constant viscosity, that is, viscosity that does not change with flow conditions.

In general, either the fluid remains stationary and an object moves through it, or the object is stationary and the fluid moves past it. The drag caused by relative motion of the fluid and a surface is a measure of the viscosity. The flow conditions must have a sufficiently small value of Reynolds number for there to be laminar flow.

At 20°C, the dynamic viscosity (kinematic viscosity × density) of water is 1.0038mPa·s and its kinematic viscosity (product of flow time × factor) is 1.0022mm2/s. These values are used for calibrating certain types of viscometers.

U-tube viscometers
These devices are also known as glass capillary viscometers or Ostwald viscometers, named after Wilhelm Ostwald. Another version is the Ubbelohde viscometer, which consists of a U-shaped glass tube held vertically in a controlled temperature bath. In one arm of the U is a vertical section of precise narrow bore (the capillary). Above there is a bulb, with it is another bulb lower down on the other arm. In use, liquid is drawn into the upper bulb by suction, then allowed to flow down through the capillary into the lower bulb. Two marks (one above and one below the upper bulb) indicate a known volume. The time taken for the level of the liquid to pass between these marks is proportional to the kinematic viscosity. The calibration can be done using a fluid of known properties. Most commercial units are provided with a conversion factor.

The time required for the test liquid to flow through a capillary of a known diameter of a certain factor between two marked points is measured. By multiplying the time taken by the factor of the viscometer, the kinematic viscosity is obtained.

Such viscometers can be classified as direct-flow or reverse-flow. Reverse-flow viscometers have the reservoir above the markings, and direct-flow are those with the reservoir below the markings. Such classifications exist so that the level can be determined even when opaque or staining liquids are measured, otherwise the liquid will cover the markings and make it impossible to gauge the time the level passes the mark. This also allows the viscometer to have more than 1 set of marks to allow, therefore yielding 2 timings and allowing subsequent calculation of determinability to ensure accurate results. The use of two timings in one viscometer in a single run is only possible if the sample being measured has Newtonian properties. Otherwise the change in driving head, which in turn changes the shear rate, will produce a different viscosity for the two bulbs.

Falling-sphere viscometers
Stokes' law is the basis of the falling-sphere viscometer, in which the fluid is stationary in a vertical glass tube. A sphere of known size and density is allowed to descend through the liquid. If correctly selected, it reaches terminal velocity, which can be measured by the time it takes to pass two marks on the tube. Electronic sensing can be used for opaque fluids. Knowing the terminal velocity, the size and density of the sphere, and the density of the liquid, Stokes' law can be used to calculate the viscosity of the fluid. A series of steel ball bearings of different diameter are normally used in the classic experiment to improve the accuracy of the calculation. The school experiment uses glycerol as the fluid, and the technique is used industrially to check the viscosity of fluids used in processes. It includes many different oils and polymer liquids.

In 1851, George Gabriel Stokes derived an expression for the frictional force (also called drag force) exerted on spherical objects with very small Reynolds numbers (e.g., very small particles) in a continuous viscous fluid by changing the small fluid-mass limit of the generally unsolvable Navier–Stokes equations:

 * $$F = 6 \pi r \eta v,$$

where
 * $$F$$ is the frictional force,
 * $$r$$ is the radius of the spherical object,
 * $$\eta$$ is the fluid viscosity,
 * $$v$$ is the particle velocity.

If the particles are falling in the viscous fluid by their own weight, then a terminal velocity, also known as the settling velocity, is reached when this frictional force combined with the buoyant force exactly balance the gravitational force. The resulting settling velocity (or terminal velocity) is given by

 * $$V_\text{s} = \frac{2}{9} \frac{r^2 g (\rho_p - \rho_f)}{\mu},$$

where:
 * $V_{s}$ is the particle settling velocity (m/s), vertically downwards if $ρ_{p} > ρ_{f}$, upwards if $ρ_{p} < ρ_{f}$,
 * $r$ is the Stokes radius of the particle (m),
 * $g$ is the gravitational acceleration (m/s2),
 * $ρ_{p}$ is the density of the particles (kg/m3),
 * $ρ_{f}$ is the density of the fluid (kg/m3),
 * $μ$ is the (dynamic) fluid viscosity (Pa·s).

Note that Stokes flow is assumed, so the Reynolds number must be small.

A limiting factor on the validity of this result is the roughness of the sphere being used.

A modification of the straight falling-sphere viscometer is a rolling-ball viscometer, which times a ball rolling down a slope whilst immersed in the test fluid. This can be further improved by using a patented V plate, which increases the number of rotations to distance traveled, allowing smaller, more portable devices. The controlled rolling motion of the ball avoids turbulences in the fluid, which would otherwise occur with a falling ball. This type of device is also suitable for ship board use.

Falling-piston viscometer
Also known as the Norcross viscometer after its inventor, Austin Norcross. The principle of viscosity measurement in this rugged and sensitive industrial device is based on a piston and cylinder assembly. The piston is periodically raised by an air lifting mechanism, drawing the material being measured down through the clearance (gap) between the piston and the wall of the cylinder into the space formed below the piston as it is raised. The assembly is then typically held up for a few seconds, then allowed to fall by gravity, expelling the sample out through the same path that it entered, creating a shearing effect on the measured liquid, which makes this viscometer particularly sensitive and good for measuring certain thixotropic liquids. The time of fall is a measure of viscosity, with the clearance between the piston and inside of the cylinder forming the measuring orifice. The viscosity controller measures the time of fall (time-of-fall seconds being the measure of viscosity) and displays the resulting viscosity value. The controller can calibrate the time-of-fall value to cup seconds (known as efflux cup), Saybolt universal second (SUS) or centipoise.

Industrial use is popular due to simplicity, repeatability, low maintenance and longevity. This type of measurement is not affected by flow rate or external vibrations. The principle of operation can be adapted for many different conditions, making it ideal for process control environments.

Oscillating-piston viscometer
Sometimes referred to as electromagnetic viscometer or EMV viscometer, was invented at Cambridge Viscosity (Formally Cambridge Applied Systems) in 1986. The sensor (see figure below) comprises a measurement chamber and magnetically influenced piston. Measurements are taken whereby a sample is first introduced into the thermally controlled measurement chamber where the piston resides. Electronics drive the piston into oscillatory motion within the measurement chamber with a controlled magnetic field. A shear stress is imposed on the liquid (or gas) due to the piston travel, and the viscosity is determined by measuring the travel time of the piston. The construction parameters for the annular spacing between the piston and measurement chamber, the strength of the electromagnetic field, and the travel distance of the piston are used to calculate the viscosity according to Newton's law of viscosity. The oscillating-piston viscometer technology has been adapted for small-sample viscosity and micro-sample viscosity testing in laboratory applications. It has also been adapted to high-pressure viscosity and high-temperature viscosity measurements in both laboratory and process environments. The viscosity sensors have been scaled for a wide range of industrial applications, such as small-size viscometers for use in compressors and engines, flow-through viscometers for dip coating processes, in-line viscometers for use in refineries, and hundreds of other applications. Improvements in sensitivity from modern electronics, is stimulating a growth in oscillating-piston viscometer popularity with academic laboratories exploring gas viscosity.

Vibrational viscometers
Vibrational viscometers date back to the 1950s Bendix instrument, which is of a class that operates by measuring the damping of an oscillating electromechanical resonator immersed in a fluid whose viscosity is to be determined. The resonator generally oscillates in torsion or transversely (as a cantilever beam or tuning fork). The higher the viscosity, the larger the damping imposed on the resonator. The resonator's damping may be measured by one of several methods:

 * 1) Measuring the power input necessary to keep the oscillator vibrating at a constant amplitude. The higher the viscosity, the more power is needed to maintain the amplitude of oscillation.
 * 2) Measuring the decay time of the oscillation once the excitation is switched off. The higher the viscosity, the faster the signal decays.
 * 3) Measuring the frequency of the resonator as a function of phase angle between excitation and response waveforms. The higher the viscosity, the larger the frequency change for a given phase change.

The vibrational instrument also suffers from a lack of a defined shear field, which makes it unsuited to measuring the viscosity of a fluid whose flow behaviour is not known beforehand.

Vibrating viscometers are rugged industrial systems used to measure viscosity in the process condition. The active part of the sensor is a vibrating rod. The vibration amplitude varies according to the viscosity of the fluid in which the rod is immersed. These viscosity meters are suitable for measuring clogging fluid and high-viscosity fluids, including those with fibers (up to 1000 Pa·s). Currently, many industries around the world consider these viscometers to be the most efficient system with which to measure the viscosities of a wide range of fluids; by contrast, rotational viscometers require more maintenance, are unable to measure clogging fluid, and require frequent calibration after intensive use. Vibrating viscometers have no moving parts, no weak parts and the sensitive part is typically small. Even very basic or acidic fluids can be measured by adding a protective coating, such as enamel, or by changing the material of the sensor to a material such as 316L stainless steel. Vibrating viscometers are the most widely used inline instrument to monitor the viscosity of the process fluid in tanks, and pipes.

Quartz viscometer
The quartz viscometer is a special type of vibrational viscometer. Here, an oscillating quartz crystal is immersed into a fluid and the specific influence on the oscillating behavior defines the viscosity. The principle of quartz viscosimetry is based on the idea of W. P. Mason. The basic concept is the application of a piezoelectric crystal for the determination of viscosity. The high-frequency electric field that is applied to the oscillator causes a movement of the sensor and results in the shearing of the fluid. The movement of the sensor is then influenced by the external forces (the shear stress) of the fluid, which affects the electrical response of the sensor. The calibration procedure as a pre-condition of viscosity determination by means of a quartz crystal goes back to B. Bode, who facilitated the detailed analysis of the electrical and mechanical transmission behavior of the oscillating system. On the basis of this calibration, the quartz viscosimeter was developed which allows continuous viscosity determination in resting and flowing liquids.

Quartz crystal microbalance
The quartz crystal microbalance functions as a vibrational viscometer by the piezoelectric properties inherent in quartz to perform measurements of conductance spectra of liquids and thin films exposed to the surface of the crystal. From these spectra, frequency shifts and a broadening of the peaks for the resonant and overtone frequencies of the quartz crystal are tracked and used to determine changes in mass as well as the viscosity, shear modulus, and other viscoelastic properties of the liquid or thin film. One benefit of using the quartz crystal microbalance to measure viscosity is the small amount of sample required for obtaining an accurate measurement. However, due to the dependence viscoelastic properties on the sample preparation techniques and thickness of the film or bulk liquid, there can be errors up to 10% in measurements in viscosity between samples.

An interesting technique to measure the viscosity of a liquid using a quartz crystal microbalance which improves the consistency of measurements uses a drop method. Instead of creating a thin film or submerging the quartz crystal in a liquid, a single drop of the fluid of interest is dropped on the surface of the crystal. The viscosity is extracted from the shift in the frequency data using the following equation

$$\Delta f = -f_0^{3/2}\sqrt{\frac{\eta_l \rho_l}{\pi \mu_Q \rho_Q}}$$

where $$f_0$$ is the resonant frequency, $$\rho_l$$ is the density of the fluid, $$\mu_Q$$ is the shear modulus of the quartz, and $$\rho_Q$$ is the density of the quartz. An extension of this technique corrects the shift in the resonant frequency by the size of the drop deposited on the quartz crystal.

Rotational viscometers
Rotational viscometers use the idea that the torque required to rotate an object in a fluid is a function of the viscosity of that fluid. They measure the torque required to rotate a disk or bob in a fluid at a known speed.

"Cup and bob" viscometers work by defining the exact volume of a sample to be sheared within a test cell; the torque required to achieve a certain rotational speed is measured and plotted. There are two classical geometries in "cup and bob" viscometers, known as either the "Couette" or "Searle" systems, distinguished by whether the cup or bob rotates. The rotating cup is preferred in some cases because it reduces the onset of Taylor vortices at very high shear rates, but the rotating bob is more commonly used, as the instrument design can be more flexible for other geometries as well.

"Cone and plate" viscometers use a narrow-angled cone in close proximity to a flat plate. With this system, the shear rate between the geometries is constant at any given rotational speed. The viscosity can easily be calculated from shear stress (from the torque) and shear rate (from the angular velocity).

If a test with any geometries runs through a table of several shear rates or stresses, the data can be used to plot a flow curve, that is a graph of viscosity vs shear rate. If the above test is carried out slowly enough for the measured value (shear stress if rate is being controlled, or conversely) to reach a steady value at each step, the data is said to be at "equilibrium", and the graph is then an "equilibrium flow curve". This is preferable over non-equilibrium measurements, as the data can usually be replicated across multiple other instruments or with other geometries.

Calculation of shear rate and shear stress form factors
Rheometers and viscometers work with torque and angular velocity. Since viscosity is normally considered in terms of shear stress and shear rates, a method is needed to convert from "instrument numbers" to "rheology numbers". Each measuring system used in an instrument has its associated "form factors" to convert torque to shear stress and to convert angular velocity to shear rate.

We will call the shear stress form factor $C_{1}$ and the shear rate factor $C_{2}$.

 * shear stress = torque ÷ $C_{1}$.
 * shear rate = $C_{2}$ × angular velocity.
 * For some measuring systems such as parallel plates, the user can set the gap between the measuring systems. In this case the equation used is
 * shear rate = $C_{2}$ × angular velocity / gap.
 * viscosity = shear stress / shear rate.

The following sections show how the form factors are calculated for each measuring system.

Cone and plate

 * $$\begin{align}

C_1 &= \frac{3}{2} r^3, \\ C_2 &= \frac{1}{\theta}, \end{align}$$

where
 * $r$ is the radius of the cone,
 * $θ$ is the cone angle in radians.

Parallel plates

 * $$\begin{align}

C_1 &= \frac{3}{2} r^3, \\ C_2 &= \frac{3}{4} r, \end{align}$$

where $r$ is the radius of the plate.

Note: The shear stress varies across the radius for a parallel plate. The above formula refers to the 3/4 radius position if the test sample is Newtonian.

Coaxial cylinders

 * $$\begin{align}

C_1 &= 2\pi r_\text{a}^2 H, \\ C_2 &= \frac{2 r_\text{i}^2 r_\text{o}^2}{r_\text{a}^2 \left( r_\text{o}^2 - r_\text{i}^2\right)}, \end{align}$$

where:
 * $r_{a} = (ri + ro)/2$ is the average radius,
 * $r_{i}$ is the inner radius,
 * $r_{o}$ is the outer radius,
 * $H$ is the height of cylinder.

Note: $C_{1}$ takes the shear stress as that occurring at an average radius $r_{a}$.

Electromagnetically spinning-sphere viscometer (EMS viscometer)

The EMS viscometer measures the viscosity of liquids through observation of the rotation of a sphere driven by electromagnetic interaction: Two magnets attached to a rotor create a rotating magnetic field. The sample ③ to be measured is in a small test tube ②. Inside the tube is an aluminium sphere ④. The tube is located in a temperature-controlled chamber ① and set such that the sphere is situated in the centre of the two magnets.

The rotating magnetic field induces eddy currents in the sphere. The resulting Lorentz interaction between the magnetic field and these eddy currents generate torque that rotates the sphere. The rotational speed of the sphere depends on the rotational velocity of the magnetic field, the magnitude of the magnetic field and the viscosity of the sample around the sphere. The motion of the sphere is monitored by a video camera ⑤ located below the cell. The torque applied to the sphere is proportional to the difference in the angular velocity of the magnetic field $Ω_{B}$ and the one of the sphere $Ω_{S}$. There is thus a linear relationship between $(Ω_{B} − Ω_{S})/Ω_{S}$ and the viscosity of the liquid.

This new measuring principle was developed by Sakai et al. at the University of Tokyo. The EMS viscometer distinguishes itself from other rotational viscometers by three main characteristics:
 * All parts of the viscometer that come in direct contact with the sample are disposable and inexpensive.
 * The measurements are performed in a sealed sample vessel.
 * The EMS viscometer requires only very small sample quantities (0.3 mL).

Stabinger viscometer
By modifying the classic Couette-type rotational viscometer, it is possible to combine the accuracy of kinematic viscosity determination with a wide measuring range.

The outer cylinder of the Stabinger viscometer is a sample-filled tube that rotates at constant speed in a temperature-controlled copper housing. The hollow internal cylinder – shaped as a conical rotor – is centered within the sample by hydrodynamic lubrication effects and centrifugal forces. In this way all bearing friction, an inevitable factor in most rotational devices, is fully avoided. The rotating fluid's shear forces drive the rotor, while a magnet inside the rotor forms an eddy current brake with the surrounding copper housing. An equilibrium rotor speed is established between driving and retarding forces, which is an unambiguous measure of the dynamic viscosity. The speed and torque measurement is implemented without direct contact by a Hall-effect sensor counting the frequency of the rotating magnetic field. This allows a highly precise torque resolution of 50 pN·m and a wide measuring range from 0.2 to 30,000 mPa·s with a single measuring system. A built-in density measurement based on the oscillating U-tube principle allows the determination of kinematic viscosity from the measured dynamic viscosity employing the relation
 * $$\nu = \frac{\eta}{\rho},$$

where:
 * $ν$ is the kinematic viscosity (mm2/s),
 * $η$ is the dynamic viscosity (mPa·s),
 * $ρ$ is the density (g/cm3).

Bubble viscometer
Bubble viscometers are used to quickly determine kinematic viscosity of known liquids such as resins and varnishes. The time required for an air bubble to rise is directly proportional to the viscosity of the liquid, so the faster the bubble rises, the lower the viscosity. The alphabetical-comparison method uses 4 sets of lettered reference tubes, A5 through Z10, of known viscosity to cover a viscosity range from 0.005 to 1,000 stokes. The direct-time method uses a single 3-line times tube for determining the "bubble seconds", which may then be converted to stokes.

This method is considerably accurate, but the measurements can vary due to variances in buoyancy because of the changing in shape of the bubble in the tube. However, this does not cause any sort of serious miscalculation.

Rectangular-slit viscometer
The basic design of a rectangular-slit viscometer/rheometer consists of a rectangular-slit channel with uniform cross-sectional area. A test liquid is pumped at a constant flow rate through this channel. Multiple pressure sensors flush-mounted at linear distances along the stream-wise direction measure pressure drop as depicted in the figure:

Measuring principle: The slit viscometer/rheometer is based on the fundamental principle that a viscous liquid resists flow, exhibiting a decreasing pressure along the length of the slit. The pressure decrease or drop ($∆P$) is correlated with the shear stress at the wall boundary. The apparent shear rate is directly related to the flow rate and the dimension of the slit. The apparent shear rate, the shear stress, and the apparent viscosity are calculated:

 * $$\begin{align}

\dot{\gamma}_\text{a} &= \frac{6Q}{wh^2}, \\ \sigma &= \frac{wh}{2(w + h)} \frac{\Delta P}{l}, \\ \eta_\text{a} &= \frac{\sigma}{\dot{\gamma}_\text{a}}, \end{align}$$

where
 * $$\dot{\gamma}$$ is the apparent shear rate (s−1),
 * $σ$ is the shear stress (Pa),
 * $η_{a}$ is the apparent viscosity (Pa·s),
 * $∆P$ is the pressure difference between the leading pressure sensor and the last pressure sensor (Pa),
 * $Q$ is the flow rate (ml/s),
 * $w$ is the width of the flow channel (mm),
 * $h$ is the depth of the flow channel (mm),
 * $l$ is the distance between the leading pressure sensor and the last pressure sensor (mm).

To determine the viscosity of a liquid, the liquid sample is pumped through the slit channel at a constant flow rate, and the pressure drop is measured. Following these equations, the apparent viscosity is calculated for the apparent shear rate. For a Newtonian liquid, the apparent viscosity is the same as the true viscosity, and the single shear-rate measurement is sufficient. For non-Newtonian liquids, the apparent viscosity is not true viscosity. In order to obtain true viscosity, the apparent viscosities are measured at multiple apparent shear rates. Then true viscosities $η$ at various shear rates are calculated using Weissenberg–Rabinowitsch–Mooney correction factor:

 * $$\frac{1}{\eta} = \frac{1}{2\eta_\text{a}}\left(2 + \frac{\mathrm{d} \ln{\dot{\gamma}_\text{a}} }{\mathrm{d} \ln{\sigma}}\right).$$

The calculated true viscosity is the same as the cone and plate values at the same shear rate.

A modified version of the rectangular-slit viscometer/rheometer can also be used to determine apparent extensional viscosity.

Krebs Viscometer
The Krebs Viscometer uses a digital graph and a small sidearm spindle to measure the viscosity of a fluid. It is mostly used in the paint industry.

Miscellaneous viscometer types
Other viscometer types use balls or other objects. Viscometers that can characterize non-Newtonian fluids are usually called rheometers or plastometers. Some instruments like capillary or VROC® viscometers can measure both Newtonian and non-Newtonian fluids.

In the I.C.I "Oscar" viscometer, a sealed can of fluid was oscillated torsionally, and by clever measurement techniques it was possible to measure both viscosity and elasticity in the sample.

The Marsh funnel viscometer measures viscosity from the time (efflux time) it takes a known volume of liquid to flow from the base of a cone through a short tube. This is similar in principle to the flow cups (efflux cups) like the Ford, Zahn and Shell cups which use different shapes to the cone and various nozzle sizes. The measurements can be done according to ISO 2431, ASTM D1200 - 10 or DIN 53411.

The flexible-blade rheometer improves the accuracy of measurements for the lower-viscosity liquids utilizing the subtle changes in the flow field due to the flexibility of the moving or stationary blade (sometimes called wing or single-side-clamped cantilever).

A rotating disk viscometer is the standard viscometer for measuring material viscosity and scorch time for rubber before vulcanization.

title: Viscometer