1851

1810–1859	USA [agriculture]	US cotton production, the vast majority of which is grown in the southern states, rises from 171,000 bales in 1810 to just under 5.4 million in 1859.
1840–1860	world [plagues and epidemics]	A cholera pandemic kills millions of people worldwide.
1845–1958	Germany [earth sciences]	German naturalist and explorer Alexander von Humboldt lays the basis of modern geography with the publication of Kosmos/Cosmos, in which he arranges geographic knowledge in a systematic fashion.
1851	UK, USA [farming]	There is a record number of Irish immigrants to the USA, in the wake of the 1845 potato crop failure.
1851	USA [clothing and fashion]	As the USA becomes increasingly wealthy, women's fashions grow more expensive, with much use of silk and velvet.
1851	USA [fiction]	The US writer Herman Melville publishes his novel Moby Dick, or the Whale, his major work and one of the great US novels of the 19th century.
1851	UK [social customs]	For the first time, more than 50% of the British population is urban. This is mainly caused by the growth of industries, particularly in the textile industry.
1851	USA [materials]	US industrialist William Kelly develops a method of removing impurities from pig iron by blowing air through the molten mass. In oxidizing the carbon impurities, the temperature rises and the process can be used to produce wrought iron or steel. It results in the production of large quantities of cheap steel.
1851	UK [newspapers]	German businessman Paul Julius, Baron von Reuter, founds the Reuters News Agency, in London, England.
1851	Italy, UK, USA [opera]	The opera Rigoletto by the Italian composer Giuseppe Fortunino Francesco Verdi is first performed, in Venice, Italy. It is based on the play Le Roi s'amuse/The King Amuses Himself, published in 1832 by Victor Hugo. The opera is first performed in Britain in 1853 (in London, England), and in the USA in 1855 (in New York City).
1851	England [photography]	The English sculptor F Scott Archer develops the wet-collodion photographic process. Collodion-coated (nitrocellulose) glass plates are exposed in the camera while still wet and then developed and fixed immediately. It permits instantaneous exposures but requires photographers in the field to take portable darkrooms.
1851	England [photography]	The English scientist William Henry Fox Talbot takes the first high-speed flash photograph. He uses a spark produced from the discharge of a Leyden jar battery for the flash.
1851–1860	world [photography]	Photographic exposure times become short enough to capture movement.
1851	France [physics]	French scientist Jean-Bernard-Léon Foucault proves that the Earth rotates by using a pendulum 67 m/220 ft long in Paris, France. The pendulum always swings in the same plane and the Earth rotates underneath it.
1851	China, Germany, France, UK, Ireland, Italy, USA, Austrian Empire [statistics and demography]	Populations (in millions) are China, 430; German States and free cities, 34; France, 33; Britain, 20.8; Ireland, 6.5; Italy, 24; USA, 23; Austrian Empire, 16.
1851–1860	USA, UK [statistics and demography]	Emigration to the USA from Britain is 423,964, and from Ireland, 914,119.
1851	UK [other structures]	The Crystal Palace, in London, England, designed by the English architect and gardener Joseph Paxton, is completed. Designed to house the Great Exhibition of 1851, it is of a revolutionary design employing only prefabricated units of glass and iron and is the largest building in the world, 563 m/1,847 ft long, 139 m/456 ft wide, and 31 m/108 ft tall. It is destroyed by fire in 1936.
1 February 1851	England [births and deaths]	Mary Wollstonecraft Shelley, English writer, author of Frankenstein, dies in London, England (53).
15 March 1851	France [education]	An act drawn up by the French minister of education, Frederick, Vicomte de Falloux, is passed, reintroducing clerical control of education in France.
16 March 1851	Spain [political events]	Spain agrees a concordat with the papacy by which Catholicism becomes the sole faith in Spain and the church gains control of education and the press.
1 May - 18 September 1851	UK [buildings]	The Great Exhibition is held in Hyde Park, London, England. Devised by Prince Albert, it is the first exhibition to display the latest technical innovations in industry, from both Britain and Europe. Exhibits are housed in the Crystal Palace, a large iron and glass structure, designed by English architect Joseph Paxton.
10 July 1851	France [births and deaths]	Louis Daguerre, French painter and physicist who invented the first practical method of photography, the daguerreotype, dies in Bry-sur-Marne, France (62).
12 August 1851	USA [tools]	US inventor Isaac Merrit Singer patents the first practical domestic sewing machine for general use, in Boston, Massachusetts. His design, which enables continuous and curved stitching, and allows any part of the material to be worked on, sets the pattern for all subsequent sewing machines.
14 September 1851	USA [births and deaths]	James Fenimore Cooper, US novelist who wrote of life on the frontier, dies in Cooperstown, New York (61).
18 September 1851	USA [newspapers]	The New York Times newspaper is launched in the USA, edited by Henry J Raymond.
2 December 1851	France [political events]	The French president, Louis-Napoléon Bonaparte, carries out a coup d'état to extend his presidency and give him more power.
19 December 1851	England [births and deaths]	J(oseph) M(allord) W(illiam) Turner, English Romantic landscape painter, dies in London, England (76).
31 December 1851	Austrian Empire [law and government]	The Austrian constitution of 1849 is abolished, consolidating the return to conservative rule in the Habsburg Empire.