* Frederick William Cumberland ( 1821 – 1881 ), engineer and politician

The US natural gas industry started in 1821 at Fredonia, Chautauqua County, New York, when William Hart dug a well to a depth of into gas-bearing shale, then drilled a borehole further, and piped the natural gas to a nearby inn where it was burned for illumination.

The island's first known sighting by Europeans was on 21 August 1821 by the British ship Eliza Francis ( or Eliza Frances ) owned by Edward, Thomas and William Jarvis and commanded by Captain Brown.

* 1821 – William Poole, American gangster ( d. 1855 )

* 1821 – William Henry Vanderbilt, American businessman ( d. 1885 )

* 1821 – Princess Elizabeth of Clarence, daughter of King William IV, granddaughter of King George III ( b. 1820 )

* 1821 – William Jervois, English engineer and caption, 10th Governor of South Australia ( d. 1897 )

* William I, Elector of Hesse ( 1743 – 1821 )

William Gladstone was educated from 1816 to 1821 at a preparatory school at the vicarage of St Thomas's Church at Seaforth, close to his family's residence, Seaforth House.

In 1821 William followed in the footsteps of his older brothers and attended Eton College before matriculating in 1828 at Christ Church, Oxford, where he read Classics and Mathematics, although he had no great interest in mathematics.

* December 8 – William Henry Vanderbilt, American entrepreneur ( b. 1821 )

* December 11 – William Milligan, Scottish theologian ( b. 1821 )

* March 8 – William Poole, infamous member of New York City's Bowery Boys gang ( b. 1821 )

William Conybeare named it Plesiosaurus ( near lizard ) because he thought it more like modern reptiles than the ichthyosaur had been, and he described it in the same 1821 paper he co-authored with Henry De la Beche on ichthyosaur anatomy.

This period included a panoply of international ‘ great demographers ’ like Adolphe Quételet ( 1796 – 1874 ), William Farr ( 1807 – 1883 ), Louis-Adolphe Bertillon ( 1821 – 1883 ) and his son Jacques ( 1851 – 1922 ), Joseph Körösi ( 1844 – 1906 ), Anders Nicolas Kaier ( 1838 – 1919 ), Richard Böckh ( 1824 – 1907 ), Émile Durkheim ( 1858-1917 ), Wilhelm Lexis ( 1837 – 1914 ) and Luigi Bodio ( 1840 – 1920 ) contributed to the development of demography and to the toolkit of methods and techniques of demographic analysis.

The first white settler in the area that would become Montgomery County was William Offield, earlier of Tennessee, who arrived in 1821 with his wife Jennie ( née Laughlin ) and one child and settled near the confluence of Offield Creek and Sugar Creek, about five miles ( 8 km ) southwest of Crawfordsville.

* William Irving ( New York ), ( 1766 – 1821 ), U. S. Congressman from New York

* William Thomas Mercer ( 1821 – 1879 ), British Colonial Secretary in Hong Kong, 1859 – 1868

For about 40 years William Kelly ( 1821 – 1906 ) was his chief interpreter and continued to be a staunch supporter until his own death.

During 1821 the President of the Board of Trade, William Huskisson, composed a Commons Committee report which recommended a return to the " practically free " trade of the pre-1815 years.

Its most notable member was the classicist William Kelly ( 1821 – 1906 ).

* William Smith ( congressman ), member of the U. S. House of Representatives from Virginia ( 1821 – 1827 )

* William Durkee Williamson ( 1779 – 1846 ) a governor of Maine ( 1821 ) was born in town.

In 1821, William and Jennie Offield had built a cabin on a little creek, later to be known as Offield Creek, four miles southwest of the future site of Crawfordsville.

He became an avid fossil collector and illustrator, collaborating with William Conybeare on an important paper on ichthyosaur and plesiosaur anatomy that was presented before the Society in 1821.

* 1812 – 1821 John Josias Conybeare

Conybeare and De la Beche coined the name for scattered finds from the Bristol region, Dorset, and Lyme Regis in 1821.

* John Josias Conybeare ( 1779 – 1824 ), became vicar of Batheaston, and was Professor of Anglo-Saxon ( 1808 – 1812 ), and afterwards Professor of Poetry ( 1812 – 1821 ), at Oxford.

The earliest patent was taken out by Henry Palmer in the UK in 1821, and the design was employed at Deptford Dockyard in South-East London, and a short line for moving stone from a quarry near Cheshunt, Hertfordshire to the River Lea.

According to Henry Petroski, transcendentalist philosopher Henry David Thoreau discovered how to make a good pencil out of inferior graphite using clay as the binder ; this invention was prompted by his father's pencil factory in Concord, which employed graphite found in New Hampshire in 1821 by Charles Dunbar.

Clay and his wife had eleven children ( six daughters and five sons ): Henrietta ( 1800 – 1801 ), Theodore ( 1802 – 1870 ), Thomas ( 1803 – 1871 ), Susan ( 1805 – 1825 ), Anne ( 1807 – 1835 ), Lucretia ( 1809 – 1823 ), Henry, Jr .( 1811 – 1847 ), Eliza ( 1813 – 1825 ), Laura ( 1815 – 1817 ), James Brown ( 1817 – 1864 ), and John ( 1821 – 1887 ).

Henry County, Georgia was created by the Georgia State Legislature in 1821 from land acquired from the Creek Indian Nation by the First Treaty of Indian Springs.

The City of Jackson was founded by an act of the Tennessee General Assembly, passed in 1821, entitled an " act to establish a seat of justice for Henry, Carroll, Henderson and Madison Counties.

* Henry Alexander Douglas ( 1821 – 1875 ), Bishop

In 1821 the town of Hamburg was established by the mechanical genius and entrepreneur Henry Shultz in direct commercial competition with Augusta.

Robert Stewart was born in Henry Street, Dublin, Ireland, in 1769 the son of Robert Stewart ( 1739 – 1821 ) of Newtownards and Comber in County Down, with properties in Counties Donegal and Londonderry.

* Henry Edwyn Chandos Scudamore-Stanhope, 9th Earl of Chesterfield ( 1821 – 1887 )

* Sir Henry Edwyn Chandos Scudamore-Stanhope, 3rd Baronet ( 1821 – 1887 ) ( succeeded as Earl of Chesterfield in 1883 )

* Henry J. Todd, Memoirs of the Life and Writings of Walton ( London, 1821 ), in 2 vols., of which the second contains a reprint of Walton's answer to Owen

He had ten children, including five sons, Henry ( 1818 – 1855 ), Ernest ( 1819 – 1903 ), Karl ( 1821 – 1887 ), Georg ( 1824 – 1896 ) and Theodor ( 1832 – 1892 ).

* Henry Bogart ( 1729 – 1821 ), American surveyor and alderman

* George LaBarre Galleries: Henry Dearborn autographed as President, Republican Institution Certificate dated 1821.

** John Henry Campbell ( 1821 – 1837 ) ( eldest son of the 7th Duke, died young )

Henry Thomas Buckle ( 24 November 1821 – 29 May 1862 ) was an English historian, author of an unfinished History of Civilization.

* Henry and Elizabeth Brocklebank 1821 pg 19

** William Henry Vanderbilt ( 1821 – 1885 )

After settling in Plymouth, James inherited his father's position as sheriff and Mercy bore him five sons, James ( 1757 – 1821 ), Winslow ( 1759 – 1791 ), Charles ( 1762 – 1784 ), Henry ( 1764 – 1828 ), and George ( 1766 – 1800 ).

He married his second wife Caroline Gifford on 29 October 1821 and she had a daughter and four sons: Barbara Augusta ( b. 9 August 1822 ), John Fox Fitz-Giffard ( b. 20 November 1823 ), Charles Orville January ( b. 1825 ), Euphrates Henry April ( b. 1826 ) and William Harper ( b. April 1827 ).