measuring fields

 

астатический измерительный прибор
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[Я.Н.Лугинский, М.С.Фези-Жилинская, Ю.С.Кабиров. Англо-русский словарь по электротехнике и электроэнергетике, Москва]

Тематики

• электротехника, основные понятия

EN

• astatic instrument

 

астатический прибор
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[IEV number 312-02-05]

EN

astatic instrument
measuring instrument in which the measuring element is, by design, unaffected by uniform magnetic fields of external origin
[IEV number 312-02-05]

FR

appareil astatique
appareil de mesure dont l'élément de mesure est, par conception, insensible aux champs magnétiques uniformes d'origine extérieure
[IEV number 312-02-05]

Тематики

• измерение электр. величин в целом

EN

• astatic instrument

DE

• Messgerät mit magnetischer Schirmung

FR

• appareil astatique

SUBJECT AREA: Recording

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He graduated from the Dover Academy (Delaware) in 1882 and was apprenticed in a machine-repair firm in Philadelphia and studied in evening classes at the Spring Garden Institute. In 1888 he took employment in a small Philadelphia machine shop owned by Andrew Scull, specializing in repair and bookbinding machinery. After travels in the western part of the US, in 1891 he became a partner in Scull \& Johnson, Manufacturing Machinists, and established a further company, the New Jersey Wire Stitching Machine Company. He bought out Andrew Scull's interest in October 1894 (the last instalment being paid in 1897) and became an independent general machinist. In 1896 he had perfected a spring motor for the Berliner flat-disc gramophone, and he started experimenting with a more direct method of recording in a spiral groove: that of cutting in wax. Co-operation with Berliner eventually led to the incorporation of the Victor Talking Machine Company in 1901. The innumerable court cases stemming from the fact that so many patents for various elements in sound recording and reproduction were in very many hands were brought to an end in 1903 when Johnson was material in establishing cross-licencing agreements between Victor, Columbia Graphophone and Edison to create what is known as a patent pool. Early on, Johnson had a thorough experience in all matters concerning the development and manufacture of both gramophones and records. He made and patented many major contributions in all these fields, and his approach was very business-like in that the contribution to cost of each part or process was always a decisive factor in his designs. This attitude was material in his consulting work for the sister company, the Gramophone Company, in London before it set up its own factories in 1910. He had quickly learned the advantages of advertising and of providing customers with durable equipment and records. This motivation was so strong that Johnson set up a research programme for determining the cause of wear in records. It turned out to depend on groove profile, and from 1911 one particular profile was adhered to and processes for transforming the grooves of valuable earlier records were developed. Without precise measuring instruments, he used the durability as the determining factor. Johnson withdrew more and more to the role of manager, and the Victor Talking Machine Company gained such a position in the market that the US anti-trust legislation was used against it. However, a generation change in the Board of Directors and certain erroneous decisions as to product line started a decline, and in February 1926 Johnson withdrew on extended sick leave: these changes led to the eventual sale of Victor. However, Victor survived due to the advent of radio and the electrification of replay equipment and became a part of Radio Corporation of America. In retirement Johnson took up various activities in the arts and sciences and financially supported several projects; his private yacht was used in 1933 in work with the Smithsonian Institution on a deep-sea hydrographie and fauna-collecting expedition near Puerto Rico.

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SUBJECT AREA: Aerospace, Weapons and armour

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Maxim was born the son of a pioneer farmer who later became a wood turner. Young Maxim was first apprenticed to a carriage maker and then embarked on a succession of jobs before joining his uncle in his engineering firm in Massachusetts in 1864. As a young man he gained a reputation as a boxer, but it was his uncle who first identified and encouraged Hiram's latent talent for invention.

It was not, however, until 1878, when Maxim joined the first electric-light company to be established in the USA, as its Chief Engineer, that he began to make a name for himself. He developed an improved light filament and his electric pressure regulator not only won a prize at the first International Electrical Exhibition, held in Paris in 1881, but also resulted in his being made a Chevalier de la Légion d'honneur. While in Europe he was advised that weapons development was a more lucrative field than electricity; consequently, he moved to England and established a small laboratory at Hatton Garden, London. He began by investigating improvements to the Gatling gun in order to produce a weapon with a faster rate of fire and which was more accurate. In 1883, by adapting a Winchester carbine, he successfully produced a semi-automatic weapon, which used the recoil to cock the gun automatically after firing. The following year he took this concept a stage further and produced a fully automatic belt-fed weapon. The recoil drove barrel and breechblock to the vent. The barrel then halted, while the breechblock, now unlocked from the former, continued rearwards, extracting the spent case and recocking the firing mechanism. The return spring, which it had been compressing, then drove the breechblock forward again, chambering the next round, which had been fed from the belt, as it did so. Keeping the trigger pressed enabled the gun to continue firing until the belt was expended. The Maxim gun, as it became known, was adopted by almost every army within the decade, and was to remain in service for nearly fifty years. Maxim himself joined forces with the large British armaments firm of Vickers, and the Vickers machine gun, which served the British Army during two world wars, was merely a refined version of the Maxim gun.

Maxim's interests continued to occupy several fields of technology, including flight. In 1891 he took out a patent for a steam-powered aeroplane fitted with a pendulous gyroscopic stabilizer which would maintain the pitch of the aeroplane at any desired inclination (basically, a simple autopilot). Maxim decided to test the relationship between power, thrust and lift before moving on to stability and control. He designed a lightweight steam-engine which developed 180 hp (135 kW) and drove a propeller measuring 17 ft 10 in. (5.44 m) in diameter. He fitted two of these engines into his huge flying machine testrig, which needed a wing span of 104 ft (31.7 m) to generate enough lift to overcome a total weight of 4 tons. The machine was not designed for free flight, but ran on one set of rails with a second set to prevent it rising more than about 2 ft (61 cm). At Baldwyn's Park in Kent on 31 July 1894 the huge machine, carrying Maxim and his crew, reached a speed of 42 mph (67.6 km/h) and lifted off its rails. Unfortunately, one of the restraining axles broke and the machine was extensively damaged. Although it was subsequently repaired and further trials carried out, these experiments were very expensive. Maxim eventually abandoned the flying machine and did not develop his idea for a stabilizer, turning instead to other projects. At the age of almost 70 he returned to the problems of flight and designed a biplane with a petrol engine: it was built in 1910 but never left the ground.

In all, Maxim registered 122 US and 149 British patents on objects ranging from mousetraps to automatic spindles. Included among them was a 1901 patent for a foot-operated suction cleaner. In 1900 he became a British subject and he was knighted the following year. He remained a larger-than-life figure, both physically and in character, until the end of his life.

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See also: Pilcher, Percy Sinclair

CM / JDS