The Russian abacus was brought to France around 1820 by the mathematician Jean-Victor Poncelet, who served in Napoleon's army and had been a prisoner of war in Russia.

As well as holding positions at this school until 1828, in 1819 and 1820 Ampère offered courses in philosophy and astronomy, respectively, at the University of Paris, and in 1824 he was elected to the prestigious chair in experimental physics at the Collège de France.

Australian English started diverging from British English after the founding of the colony of New South Wales in 1788 and was recognised as being different from British English by 1820.

Anne Brontë (; 17 January 1820 – 28 May 1849 ) was a British novelist and poet, the youngest member of the Brontë literary family.

Anne, the youngest member of the Brontë children, was born on 17 January 1820, at 74 Market Street in Thornton where her father was curate and she was baptised there on 25 March 1820.

* Daniel Boone ( November 2, 1734 October 22 – September 26, 1820 ) was an American pioneer, explorer, and frontiersman whose frontier exploits made him one of the first folk heroes of the United States.

A significant contribution to the chemistry of alkaloids in the early years of its development was made by the French researchers Pierre Joseph Pelletier and Joseph Bienaimé Caventou, who discovered quinine ( 1820 ) and strychnine ( 1818 ).

In 1820 the city wall was torn down, with the exception of the individual towers and gates, and the defensive ditches were filled in.

The relation between electric current, magnetic fields and physical forces was first noted by Hans Christian Ørsted who, in 1820, observed a compass needle was deflected from pointing North when a current flowed in an adjacent wire.

The trumpet was a natural brass instrument prior to about 1795, and the horn before about 1820.

The composer Manuel Robles and the poet Bernardo de Vera y Pintado fulfilled this mandate and their " National Song " debuted on 20 August 1820 in the Domingo Arteaga theater, although other historians claim that it was played and sung during the festivities of September 1819.

Therefore, by the end of the decade, some Cubans were inspired by the successes of Simón Bolívar, despite the fact that the Spanish Constitution was restored in 1820.

When the whaleship Essex was rammed and sunk by a whale in 1820, the captain opted to sail 3000 miles upwind to Chile rather than 1400 miles downwind to the Marquesas because he had heard the Marquesans were cannibals.

In 1820, the colony of Cape Breton Island was merged for the second time with Nova Scotia.

The symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating the eponymous Ampère's force law which he discovered in 1820.

The land which is now Columbus was bought by General John Tipton and Luke Bonesteel in 1820.

The cornet was originally derived from the post horn around 1820 in France.

In 1820, the Colony of Cape Breton Island was merged back into the Colony of Nova Scotia for the second time by the British government.

In 1784, the two provinces were divided ; Nova Scotia was split into Nova Scotia, Cape Breton Island ( rejoined to Nova Scotia in 1820 ), Prince Edward Island, and New Brunswick, while Quebec was split into Lower Canada ( southern Quebec ) and Upper Canada ( southern through lower northern Ontario ).

Up to 1820, about had been secured to settlers and by quiet possession titles, when Mr. Jarvis bought the remainder.

In 1820, the Crown bought the area surrounding the waterways.

Batchworth Mill was later used as a cotton mill, but was bought in 1820 by Messrs. John Dickinson & Co., and converted into paper mills, now the site of Veolia Water.

In 1820 the estate was bought by Jesse Watts-Russell, a wealthy industrialist.

In 1820 the land was bought by the Crown during the development of John Nash's Regent Street.

Billing Baldwin, an industrialist in Kings Norton, had bought the house in 1872 from the son of John Merry, who in turn had purchased the house in 1820.

The Cookridge Estate was bought by Richard Wormald in 1820 and sold in portions by his descendant Francis Wormald in the 1920s.

It is located on Town Street () and was an inn until 1820, when it was bought by the parish and was used as a workhouse until 1848.

In 1820, Henry Harris bought a site in Hawkins Street and built the 2, 000 – seater Albany New Theatre on it at a cost of £ 50, 000, designed by architect Samuel Beazley.

They bought the Waterside and Bridge Mill complex from John Turner and John Thornley in 1820.

In 1755 the owners were named Livesey and John Hodson of Ellerbeck bought it in 1820.

In September of 1820, Ampère ’ s friend and eventual eulogist François Arago showed the members of the French Academy of Sciences the surprising discovery of Danish physicist Hans Christian Ørsted that a magnetic needle is deflected by an adjacent electric current.

Although myths and speculation about a Terra Australis (" Southern Land ") date back to antiquity, the first confirmed sighting of the continent of Antarctica is commonly accepted to have occurred in 1820 by the Russian expedition of Fabian Gottlieb von Bellingshausen and Mikhail Lazarev on Vostok and Mirny.

Portrait of Beethoven by Joseph Karl Stieler, 1820

In 1820, Spain abolished the slave trade, hurting the Cuban economy even more and forcing planters to buy more expensive, illegal, and troublesome slaves ( as demonstrated by the events surrounding the ship Amistad ).

The opening of the Sankey Canal in 1757, followed by the Bridgewater Canal in 1761, which halved the price of coal in Liverpool and Manchester England, respectively, triggered a period of " canal mania " in Britain so that between 1760 and 1820 over one hundred canals were built.

After the sinking of the Essex of Nantucket by a whale, on November 20, 1820, ( an important source event for Herman Melville's Moby-Dick ) the survivors, in three small boats, resorted, by common consent, to cannibalism in order for some to survive.

* Westward by Sea: A Maritime Perspective on American Expansion, 1820 – 1890, digitized source materials from Mystic Seaport, via Library of Congress American Memory

The Arithmometer, invented in 1820 as a four-operation mechanical calculator, was released to production in 1851 as an adding machine and became the first commercially successful unit ; forty years later, by 1890, about 2, 500 arithmometers had been sold plus a few hundreds more from two arithmometer clone makers ( Burkhardt, Germany, 1878 and Layton, UK, 1883 ) and Felt and Tarrant, the only other competitor in true commercial production, had sold 100 comptometers.

The Ilois, now called Chagos Islanders or Chagossians since the late 1990s, were descended primarily from slaves brought to the island from Madagascar by the French between 1793 and 1810, and Malay slaves from the slave market on Pulo Nyas, an island off the northwest coast of Sumatra, from around 1820 until the slave trade ended following the Slavery Abolition Act of 1833.

The second chapter in Ecuador's struggle for emancipation from Spanish colonial rule began in Guayaquil, where independence was proclaimed in October 1820 by a local patriotic junta under the leadership of the poet José Joaquín de Olmedo.

** The Battle of Marathon by Elizabeth Barrett Browning ( 1820 )

One of the most important discoveries relating to current was made accidentally by Hans Christian Ørsted in 1820, when, while preparing a lecture, he witnessed the current in a wire disturbing the needle of a magnetic compass.

The birth of native Estonian literature was in 1810 to 1820 when the patriotic and philosophical poems by Kristjan Jaak Peterson were published.

* 1820 – The first 86 African American immigrants sponsored by the American Colonization Society started a settlement in present-day Liberia.