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A Short History of the Galvanometer

A Short History of the Galvanometer


Image of PITH BALL ELECTROSCOPE, 1950's

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PITH BALL ELECTROSCOPE, 1950's

Pith ball for demonstrating Electrostatic energy, when the rod is rubbed with silk it generates a static charge which attracts the ball when placed in its proximity. Invented by British weaver's apprentice John Canton in 1754. This model was used by schools from the 1950's, and made by Philip Harris Ltd.

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A1528

Image of CROOKES TUBE WITH EVACUATION PORT, 1930's

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CROOKES TUBE WITH EVACUATION PORT, 1930's

For observing the Litho of discharge effects at different pressures. The invention of the diffusion pump by the German physicist Wolfgang Gaede in 1915, with important improvements by the American chemist Irving Langmuir, to which several different types of discharge tubes could be connected to remove the atmosphere.The most famous one is the Lenard tube, invented much earlier. (See The Cathode Ray tube site, Crookes tubes page 3)
The basic Crookes tube is a glass tube closed of at each end and an opening to evacuate the air. Two electrodes are sealed into the glass at each end, a voltage is placed across the tubes via the terminals and the air is gradually pumped out until a current is detect with amp meter. using this experiment scientist could learn the different characteristics of voltage flow in a vacuum. In 1855, Geissler invented the mercury vacuum pump thus making it possible to produce good quality vacuums in laboratory equipment.

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A1382

Image of ZAMBONI PILES, 1954

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ZAMBONI PILES, 1954

A Zamboni pile is an "electrostatic battery" and is constructed from discs of silver foil, zinc foil, and paper. Discs of approx. 20 mm diameter are assembled in stacks which may be several thousand discs thick and then either compressed in a glass tube. Zamboni piles have output potentials in the kilovolt range, but current output in the nanoampere range. The famous Oxford Electric Bell which has been ringing continuously since 1840 is thought to be powered by a pair of Zamboni piles.

Donated by Ken Willis

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A1359

Image of OERTLING SCIENTIFIC BALANCE, 1950's

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OERTLING SCIENTIFIC BALANCE, 1950's

By means of a prism and viewing screen, illuminated by a torch bulb, the miniature scale can be read accurately.
Air dampers in brass cylinders are used to stabilise the movement.

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A0125

Image of PHILIP HARRIS SCALES, 1950's

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PHILIP HARRIS SCALES, 1950's

Simple version of scales used in Laboratories and workshops.

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A0124

Image of OERTLING PRECISION BALANCE, 1970's

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OERTLING PRECISION BALANCE, 1970's

Model 142 Scientific Scales used by Chemists and Laboratories.

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A1043

Image of TESLA COIL, 1950's

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TESLA COIL, 1950's

The Tesla Coil was originally designed by Nicola Tesla in 1891 to produce very high voltages. His theories eventually lead to a possible means of transmitting power via a large aerial, replacing power lines, although the first aerial was made in America it never became a practicality. This is a model made for classrooms.

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A1022

Image of GRIFFIN AND GEORGE RUHMKORFF INDUCTION COIL, 1950's

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GRIFFIN AND GEORGE RUHMKORFF INDUCTION COIL, 1950's

In 1857, after examining a greatly improved version made by an American inventor, Edward Samuel Ritchie, Ruhmkorff improved his design (as did other engineers), using glass insulation and other innovations to allow the production of sparks more than 30 centimetres long.
Ruhmkorff patented the first version of his induction coil in 1851, and its success was such that in 1858 he was awarded a 50,000-franc prize by Napoleon III for the most important discovery in the application of electricity.
He died in Paris in 1877.

Bruce Hammond Collection

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A1156

Image of PHILIP HARRIS RUHMKORFF INDUCTION COIL, 1930's

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PHILIP HARRIS RUHMKORFF INDUCTION COIL, 1930's

Shown working, with the 6 inch spark.

Heinrich Daniel Ruhmkorff (January 15, 1803 in Hanover – December 20, 1877 in Paris) was a German instrument maker who commercialised the induction coil (often referred to as the Ruhmkorff coil.)
Ruhmkorff was born in Hanover. After an apprenticeship with a German mechanic, he moved to England. Biographies say that he worked with the inventor Joseph Bramah, but this is unlikely since Bramah died in 1814. He may, though, have worked for the Bramah company.
In 1855, he set up a shop in Paris, where he gained a reputation for the high quality of his electrical apparatus.

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A0947

Image of EUREKA 6 INCH RUHMKORFF INDUCTION COIL, 1930's

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EUREKA 6 INCH RUHMKORFF INDUCTION COIL, 1930's

Electromagnetic induction was discovered by Michael Faraday (1791-1867).
In 1831 Nicolas Callan (1799-1864) invented the Induction coil.
In 1836 they were used for medical complaints such as skin disorders, and to power X ray machines.
Marconi used one for his experiments prior to developing his system at Poldhu in Cornwall for the first transatlantic transmission. Coils like this were used in spark transmitter systems for the next 30 years.
Later coils such as this unit, were made for schools and Colleges as demonstration units.

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A0135

Image of 5 INCH INDUCTION COIL, 1950's

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5 INCH INDUCTION COIL, 1950's

In several of Jules Verne's science-fiction novels, so-called "Ruhmkorff lamps" are mentioned. These were an early form of portable electric lamp. The lamp consisted of a Geissler tube that was powered by a battery-powered Ruhmkorff induction coil, an example of one (made much later)is shown here.

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A0966

Image of LECLANCHE CELL, 1896

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LECLANCHE CELL, 1896

The cell was invented by Georges Leclanche' in 1866, it is the forerunner of modern Zinc Carbon dry cells. In the centre is a porous cylinder filled with Manganese Dioxide and in the centre of this is a carbon rod. Outside of the cylinder is a zinc rod. The jar would normally be filled with Ammonium Chloride. The Positive terminal is the carbon rod and the zinc is negative. The voltage obtained is 1.5 Volts.

Georges Leclanché (1839 - 1882) was a French electrical engineer chiefly remembered for his invention of the Leclanché cell; one of the first modern electrical batteries and the forerunner of the modern dry cell battery.
The original form of the cell used a porous pot. This gave it a relatively high internal resistance and various modifications were made to reduce it. These included the "Agglomerate block cell" and the "Sack cell".

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A0186

Image of GRENET CELL, 1888

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GRENET CELL, 1888

The power source used by Thomas Edison for his perfected Phonograph of 1888. The Grenet cell was invented by the German Johan Christian Poggendorff (1796-1877). Called Grenet Cell because he made a practical version possible. Used as a source of power before the Dry Battery became available. It consists of three plates in a jar filled with 17 parts potassium dichromate dissolved in 100 parts of distilled water with the addition of 22 parts sulphuric acid. The two positive plates are made of retort graphite, the negative Zinc that can be raised or lowered into the solution; this prevents corrosion when not in use. These units come in varying sizes from 1/3 to 3 Litres.

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A0185

Image of SMALL ELECTROSCOPE IN LABORATORY FLASK, 1890's

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SMALL ELECTROSCOPE IN LABORATORY FLASK, 1890's

Used for the the detection of electrostatic charges. If a charged item such as a Ebonite rod that has been rubbed is held near the the brass terminal, the small foil leaf will deflect away from the mounting.

Bruce Hammond Collection

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A1149

Image of ELECTROSCOPE, 1900's

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ELECTROSCOPE, 1900's

The Electroscope was used for the the detection of electrostatic charges. If a charged item, (such as an Ebonite rod that has been rubbed) is held near the the brass terminal, the gold leaf will deflect away from the mounting.

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A0259

Image of PHILIP HARRIS ELECTROSCOPE, 1890's

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PHILIP HARRIS ELECTROSCOPE, 1890's

Used for the the detection of electrostatic charges. If a charged item such as a Ebonite rod that has been rubbed is held near the the brass terminal, the gold leaf will deflect away from the mounting.

Bruce Hammond Collection

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A1148

Image of TANDY 160 IN ONE, 1980's

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TANDY 160 IN ONE, 1980's

Hobby kit for children and adults to learn electronics. A popular pastime from the 1900's to the 1980's. A version of this equipment can still be found today, and is still used as a teaching aid.

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A0104

Image of R & J BECK MICROSCOPE, 1900's

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R & J BECK MICROSCOPE, 1900's

Microscope for medical and scientific use in laboratories and colleges. Complete with slides lens's and accessories. James Smith, a scientific instrument maker, commenced making microscopes in 1839 and took Richard Beck into partnership in 1847 trading as Smith & Beck at 6 Coleman Street, London. In 1851 Joseph Beck, the brother of Richard Beck, started working for the firm and became a partner in 1857 when the business name became Smith, Beck & Beck. When Smith retired in 1865 the business address was 31 Cornhill and the trading name changed to R & J Beck.

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A1365

Image of MICROSCOPE, 1900's

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MICROSCOPE, 1900's

Simple brass microscope, still in excellent working order, the wooden box is very basic.

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A0126

Image of 6  GRIFFIN AND TATLOCK  VACUUM TUBES IN A RACK, 1950's

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6 GRIFFIN AND TATLOCK VACUUM TUBES IN A RACK, 1950's

The Cross vacuum scale demonstrates the phenomenon of discharge at different pressures. The pressure in the tubes varies between 40 Torr (mm/Hg), the lowest vacuum in the left tube, to 0.03 Torr the highest vacuum in the right tube.

It is in this high vacuum, used in many Crookes tubes, that X-Ray's are produced.


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A0948

Image of HILGER SPECTROMETER, 1960's

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HILGER SPECTROMETER, 1960's

A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization state. This equipment uses the 'Spekker' Principal, a Registered Trade Mark.

Donated by L.G.Bray

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A1522

Image of ABSORBIOMETER, 1940's

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ABSORBIOMETER, 1940's

A spectrometer is an optical instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization state.

Donated by Ken Willis

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A0915

Image of PHOTO ELECTRIC ABSORBIOMETER, 1950's

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PHOTO ELECTRIC ABSORBIOMETER, 1950's

Using the 'Spekker' Principal and used for the analyses of Iron. A known sample is placed on one side of the lamp, and the specimen on the other. Filters are added, and the refraction of light is used to measure the unknown sample against the known one, using a Galvanometer. This Field of research is associated with Spectrometry

Donated by Ken Willis

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A0912

Image of MAGNET, 1960's

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MAGNET, 1960's

Could have been used in experiments on Magnetrons.

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A0946

Image of GEISSLER TUBES

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GEISSLER TUBES

One tube Marked 6132 for Helium. One Marked 6130 for Nitrogen. The others marked Oxegen Hydrogen and Carbon Dioxide. Heinrich Geissler (1814-1879) The Geissler tube is a glass tube for demonstrating the principles of electrical glow discharge. The tube was invented by the German physicist and glass-blower Heinrich Geissler in 1857. The Geissler tube was an evacuated glass cylinder with an electrode at each end, it would contain one or more of the following rarefied (thinned) gasses, such as neon, argon, or air, mercury or other conductive liquids, or ionizable minerals or metals, such as sodium. When a high voltage is applied to the terminals, an electrical current flows through the tube. The current will disassociate electrons from the gas molecules, creating ions, and when electrons recombine with the ions, different lighting effects are created. The light will be characteristic of the material contained within the tube and will be composed of one or more narrow spectral lines. The museum has several Geissler Tubes which can be demonstrated.

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A0969

Image of 5 X GEISSLER TUBES, 1950's

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5 X GEISSLER TUBES, 1950's

Illuminated

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A0969

Image of CROOKES TUBE, 1950's

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CROOKES TUBE, 1950's

Used in class rooms to demonstrate high voltage effects on evacuated tubes,or Cathode Rays. Sir William Crookes circa 1875. (1832-1919) The Railway tube or Paddle Wheel demonstrates Kinetic Energy.
The electrons bounced at the paddles (which are covered
with a small amount of a Mineral which will glow for effect), this will turn
the paddle wheel and move from one end of the tube to the other.
Crookes thought that Cathode Rays had momentum, but in 1903 J.J.Thomson proved that the rays hitting the paddle heated the gas on that side causing it to expand, as the gas on the other side remained cool, the vane moved away from the ray.
The railway tube was one of the models
Crookes demonstrated in his famous lecture in
Sheffield 1879.

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A0264

Image of CROOKES TUBE, 1950's

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CROOKES TUBE, 1950's

Illuminated

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A0264

Image of CROOKES TUBE 'MALTESE CROSS', 1930's

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CROOKES TUBE 'MALTESE CROSS', 1930's

Used to demonstrate cathode rays. A negative voltage is connected to the small end and a positive connected to the cross. The tube is evacuated of air, and when the voltage is applied, electrons (cathode rays) travel from the small electrode towards the cross, some hit the cross while others carry on and illuminate the end of the tube leaving a well defined shadow. This was the first cathode ray tube, probably attributed to Johann Wilhelm Hittorf in 1869, the same period as Crookes was experimenting.

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A0265

Image of MALTESE CROSS, 1950's

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MALTESE CROSS, 1950's

Illuminated

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A0265

Image of GEISSLER TUBE, 1950's

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GEISSLER TUBE, 1950's

Used to demonstrate the effects of high voltage on liquids and gases in Schools and Universities. The yellow area is a liquid called Fluorescein, the Green Glass is Uranium Glass which is the element that glows, the elements are producing three colours in all, which glow yellow, green and violet, when hit by electrons created by a very high voltage,


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A0883

Image of GEISSLER TUBE, 1950's

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GEISSLER TUBE, 1950's

Illuminated

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A0883

Image of GEISSLER TUBE, 1950's

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GEISSLER TUBE, 1950's

Geissler tubes, were named after the man who first devised them (1814-1879), to demonstrate the effect of high voltages on different gases or air that has been rarefied. This one would have been made for a University or College. The Geissler tube is a glass tube for demonstrating the principles of electrical glow discharge. The tube was invented by the German physicist and glassblower Heinrich Geissler in 1857. The Geissler tube was an evacuated glass cylinder with an electrode at each end. A Geissler tube contains one or more of the following rarefied (thinned) gasses, such as neon, argon, or air; mercury or other conductive liquids. When a high voltage is applied to the terminals, an electrical current flows through the tube. The current will disassociate electrons from the gas molecules, creating ions, and when electrons recombine with the ions, different lighting effects are created. The light will be characteristic of the material contained within the tube and will be composed of one or more narrow spectral lines.

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A0851

Image of GEISSLER TUBE, 1950's

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GEISSLER TUBE, 1950's

Illuminated

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A0851

Image of SMALL CROOKES TUBE WITH CRYSTALS, 1890's

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SMALL CROOKES TUBE WITH CRYSTALS, 1890's

Used in class rooms to demonstrate high voltage effects on evacuated tubes and enclosed crystals. Sometimes referred to as a 'Cows Udder'.

Bruce Hammond Collection

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A1150

Image of SMALL CROOKES TUBE WITH CRYSTALS

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SMALL CROOKES TUBE WITH CRYSTALS

Illuminated

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A1150b

Image of CROOKES TUBE WITH BUTTERFLY, 1950's

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CROOKES TUBE WITH BUTTERFLY, 1950's

Used in class rooms to demonstrate high voltage effects on evacuated tubes and Chemicals. The butterfly is made of metal, coated in different minerals, when the electrons hit the elements they glow in the associated colour for that type. The principal is similar to a modern fluorescent tube. We can demonstrate this item in the museum along with a number of other electrical objects.

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A1135

Image of CROOKES TUBE WITH BUTTERFLY, 1900's

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CROOKES TUBE WITH BUTTERFLY, 1900's

Illuminated

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A1135

Image of WIMSHURST MACHINE, 1890's

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WIMSHURST MACHINE, 1890's

This electrostatic device was invented between 1880-1883 by British inventor James Wimshurst. It was used for generating high voltages, the machines were frequently used to power X Ray tubes.

The Wimshurst Machine belonged to a class of generators called influence machines, they separated electric charges through electrostatic induction or influence.

The Wimshurst Machine is self-starting, meaning it doesn’t need external electrical energy, it does however, need mechanical power and by turning the handle very quickly the two glass disks and their metal sectors rotate in opposite directions passing the crossed metal neutraliser bars and their brushes.

An imbalance of charges is induced, amplified and collected by two pairs of metal combs with points placed near the surfaces of each disk, this creates a spark, and the accumulated energy can be collected and stored in the two “Leyden Jars”

Bruce Hammond Collection

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A1153

Image of WIMSHURST GENERATOR, 1950's

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WIMSHURST GENERATOR, 1950's

Wimshurst built these machines between 1880 and 1883.

This unit was used in schools and colleges up to the early 1980's and is not antique although they are now seldom seen. It was used as a training aid in a subject that is no longer considered important in a world of computers.

The two disks rotate in opposite directions when the handle is turned. Strips of foil on the disks are rubbed with two wire brushes, static is picked up by prongs positioned close to the disks and stored in two jars (Leyden Jars). When the charge is sufficient a large spark discharges the stored energy across a gap by two brass rods.

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A0114


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