Thomas Harriot
Thomas Harriot drew the Moon through a telescope on the 5th of August 1609, four months before Galileo Galilei made his own celebrated lunar sketches. Yet Harriot's name is largely unknown outside the history of science. He was born around 1560 in Oxford and died on the 2nd of July 1621. In the decades between, he made discoveries that would normally guarantee immortality. He published almost none of them. The question that haunts his story is not what he found but why the world had to wait so long to find out.
Harriot's name appears in the St Mary Hall, Oxford registry dating from 1577. After graduating in 1580, he was hired by Sir Walter Raleigh, first as a mathematics tutor. Raleigh recognized that Harriot's knowledge of astronomy and astrology made him useful for navigation. He helped design Raleigh's ships and served as his accountant. Before the voyage, he also wrote a treatise on navigation.
Two Native Americans named Manteo and Wanchese had been brought to England before the Roanoke expedition departed. Harriot spent time with both men and devised a phonetic alphabet to transcribe their Carolina Algonquian language. He was the only Englishman who had learned it before the ships left.
The expedition reached Roanoke Island, off the coast of North Carolina, around 1585-86. Harriot interrogated Manteo closely about life in the New World. He believed the Indigenous peoples he encountered were intelligent but had access to inferior technology. He recorded their reaction to European instruments:
"Many things they sawe with us...as mathematical instruments, sea compasses...and spring clocks that seemed to goe of themselves , and many other things we had , were so strange unto them, and so farre exceeded their capacities to comprehend the reason and meanes how they should be made and done, that they thought they were rather the works of gods than men."
During the voyage, Raleigh asked Harriot to solve a practical problem: the most efficient way to stack cannonballs on a ship's deck. His answer was a theory about the close-packing of spheres. It bore a striking resemblance to atomism and modern atomic theory, and he was later accused of believing in atomism. His correspondence on optics with Johannes Kepler went on to influence Kepler's conjecture.
The account Harriot wrote of the Roanoke voyage, A Briefe and True Report of the New Found Land of Virginia, was published in 1588. It was probably written a year earlier. The book offered one of the earliest English-language accounts of the Native American population encountered by the expedition and proved influential for later English explorers and colonists.
He wrote that if "means of good government be used," the Native Americans might "in short time be brought to civility and the embracing of true religion." That view reflected the paternalistic assumptions of his era. His more nuanced observations about the intelligence and industry of the people he encountered were largely set aside by later readers. Those readers focused instead on the book's descriptions of extractable minerals and resources in Virginia.
Harriot is also sometimes credited with introducing the potato to the British Isles. The True Report shaped how England understood its early colonial venture. It remained the only work Harriot published during his lifetime. He left behind more than 400 sheets of annotated writing that would take centuries to fully understand.
After the Roanoke voyage, Harriot entered the service of Henry Percy, the 9th Earl of Northumberland. Percy provided more stable patronage than Raleigh had, and Harriot lived at Syon House, which was managed by Percy's cousin Thomas Percy. In 1595, the Earl made property in Durham over to Harriot, moving him into the ranks of the landed gentry. He also gave Harriot use of a house on the Syon estate to pursue his work in optics and the law of refraction.
Raleigh fell from favor first. Then, in 1605, the Earl of Northumberland was imprisoned in connection with the Gunpowder Plot. One of the conspirators was Thomas Percy, the man who had managed Syon House. Harriot himself was interrogated and briefly imprisoned before his release.
In 1607, Harriot observed Halley's Comet from Ilfracombe, and his notes on those observations deepened his understanding of the comet's orbit.
From 1614, Harriot was consulting Théodore de Mayerne, one of King James I's physicians. An apparent cancer of the left nostril was gradually eating away the septum. A cancerous ulcer on his lip was also part of the picture. By 1621, Harriot was living with a friend named Thomas Buckner on Threadneedle Street in London. He died on the 2nd of July 1621, three days after writing his will. Nathaniel Torporley had been designated as the intended executor of Harriot's mathematical manuscripts. Walter Warner was the one who ultimately pulled the posthumous algebra book into shape.
For his lunar work, Harriot used a 6X Dutch telescope, an instrument invented in 1608 that he had acquired early in 1609. His approach to mapping what he saw was cartographic. He treated the lunar surface as a territory to be charted in the way a navigator might chart a coastline. Galileo, by contrast, worked topographically, describing the Moon's mountains and craters in terms of their physical relief. Galileo's observations were published in his book Sidereus Nuncius in 1610 and contained greater detail, including features not previously identified.
By 1613, Harriot had produced two complete maps of the whole Moon, showing many identifiable features including lunar craters in their correct relative positions. Those maps were not surpassed for several decades. He continued observing until 1612.
Harriot's lunar records were not published until 1784, and some did not come to light until 1965. Critics including Terrie Bloom accused him of plagiarizing Galileo's depictions directly. The charge remains contested; scholars have noted that each man was concentrating on different aspects of the same object. Harriot's silence about his results may be connected to the fallout from the Gunpowder Plot.
Harriot was known to have read and admired Galileo's work in Sidereus Nuncius. The relationship between their contributions to early telescopic astronomy was more complex than simple rivalry.
Harriot documented a total of 690 observations of sunspots. He logged them in 199 drawings that captured details of the Sun's axial rotation and its acceleration. He made these observations in a direct and hazardous way, pointing his telescope at the Sun. No injuries to his eyes were ever recorded. He used telescopes of varying magnification, most often 10X and 20X power, and chose to observe after sunrise because the lower angle in the sky made the vertical axis easier to analyze.
Galileo also observed sunspots and published his findings in 1613. The existence of sunspots challenged the classical idea of the heavens as perfect and unchanging. Harriot's accumulated observations provided further support for the heliocentric theory of the solar system. The precise setup of Harriot's telescope for these observations remains largely unknown, which stands as one measure of how much about his methods has been lost.
Harriot invented binary notation and arithmetic several decades before Gottfried Wilhelm Leibniz. That fact remained unknown until the 1920s. He also discovered what is now called Snell's law of refraction some twenty years before Willebrord Snellius. He founded what became known as the "English school" of algebra. Around 1600, he introduced an algebraic symbolism close to modern notation, making computation with unknowns nearly as manageable as computation with numbers. He is credited with the first widespread use of the inequality signs "<" and ">".
Harriot is also credited with discovering what is known as Girard's theorem. The formula bears Albert Girard's name because Girard was first to publish it. Around 1620, Harriot's unpublished papers included the early basis of continuous compounding. Using logarithms and series calculations, he illustrated how compounded interest grows as intervals are shortened.
His algebra book Artis Analyticae Praxis was published posthumously in 1631. The editors did not fully understand his reasoning and removed sections they could not comprehend, including treatments of the negative and complex roots of equations. The full annotated English translation of the Praxis was not completed until 2007. De numeris triangularibus et inde de progressionibus arithmeticis: Magisteria magna is a more complete manuscript. Janet Beery and Jackie Stedall published it in facsimile form with commentary in 2009.
Some scholars have suggested that Harriot's immersion in the Carolina Algonquian language during the Roanoke voyage may have had some effect on his mathematical thinking, a connection that remains as underexplored as much of his work.
Surviving manuscripts of Harriot's work are held in the British Museum and in the archives of the Percy family. The Percy archive is split between Petworth House in Sussex and Alnwick Castle in Northumberland. Many papers have been lost. He was frequently accused of being an atheist. The literary historian Stephen Greenblatt suggested he may have deliberately avoided publication to limit those attacks, writing: "... he preferred life to fame. And who can blame him?"
The first biography of Harriot was written by Henry Stevens of Vermont in 1876 but not published until 1900. The print run was only 167 copies, and the work remained little known until a reprint appeared in 1972. American poet and biographer Muriel Rukeyser wrote The Traces of Thomas Hariot, published in 1970 and 1971. A symposium at the University of Delaware in April 1971 drew further scholarly attention, with proceedings published by Oxford University Press in 1974. John W. Shirley, who lived from 1908 to 1988, edited that volume and went on to publish a Harriot biography in 1983.
An event called Telescope400 was held at Syon House in West London in 2009 to mark the 400th anniversary of Harriot's first Moon observations. Lord Egremont unveiled a plaque there in his honor.
A crater on the Moon was named after Harriot in 1970. It sits on the far side of the Moon and is permanently invisible from Earth. In July 2014, the International Astronomical Union launched a public process for naming exoplanets. In December 2015, the IAU announced that the exoplanet 55 Cancri f had been named Harriot. The winning name was submitted by the Royal Netherlands Association for Meteorology and Astronomy.
The Thomas Harriot College of Arts and Sciences at East Carolina University in Greenville, North Carolina bears his name in recognition of his work during the Virginia expedition. The observatory at the College of William and Mary does likewise for his astronomy. Four centuries after his death, the name once almost lost to history now belongs to a world in another solar system.
Updated
Common questions
What is Thomas Harriot best known for in astronomy?
Harriot is recognized as the first astronomer to draw an astronomical object through a telescope, sketching the Moon on the 5th of August 1609, nearly four months before Galileo Galilei made his own lunar observations. He also made the first telescopic observations of sunspots in 1610, documenting 690 observations in 199 drawings.
Why did Thomas Harriot not publish his scientific discoveries?
Harriot published almost nothing during his lifetime despite making major discoveries in mathematics, optics, and astronomy. He was frequently accused of being an atheist, and the literary historian Stephen Greenblatt suggested he may have deliberately avoided publication to limit those attacks.
What mathematical contributions did Thomas Harriot make?
Harriot invented binary notation and arithmetic several decades before Gottfried Wilhelm Leibniz, though this remained unknown until the 1920s. He also discovered Snell's law of refraction twenty years before Willebrord Snellius, founded the English school of algebra, and is credited with the first widespread use of the inequality signs < and >.
Who was Thomas Harriot and when did he live?
Thomas Harriot was an English astronomer, mathematician, ethnographer, and translator, born around 1560 in Oxford, England. He died on the 2nd of July 1621, apparently from skin cancer. He worked for patrons including Sir Walter Raleigh and Henry Percy, the 9th Earl of Northumberland.
What role did Thomas Harriot play in the Roanoke expedition?
Harriot served as the sole English interpreter on the 1585-86 expedition to Roanoke Island, off the coast of North Carolina, having learned the Carolina Algonquian language from two Native Americans named Manteo and Wanchese. He later wrote A Briefe and True Report of the New Found Land of Virginia, published in 1588, which proved influential for later English explorers and colonists.
Where are Thomas Harriot's surviving manuscripts held?
Harriot's surviving manuscripts are held in the British Museum and in the archives of the Percy family at Petworth House in Sussex and Alnwick Castle in Northumberland, with many papers lost. His posthumous algebra book Artis Analyticae Praxis was published in 1631, but the full annotated English translation was not completed until 2007.
All sources
37 references cited across the entry
- 3Thomas Hariot (ca. 1560–1621)Michael Moran — 2014
- 4JournalThomas Harriot: the first telescopic astronomerA. Chapman — 2008
- 6JournalWhy Did Thomas Harriot Invent Binary?Lloyd Strickland — 2023
- 8BookThe English Literatures of America, 1500–1800Myra Jehlen et al. — Routledge — 1997
- 9BookNatives and newcomers: Canada's "Heroic Age" reconsideredBruce Trigger — McGill-Queen's Press — 1986
- 10BookA Brief and True Report of the New Found Land of Virginia (1588)Thomas Hariot — University of Nebraska-Lincoln — 1588
- 12BookDictionary of National Biography, Vol. 24: Hailes–HarriottMacmillan & Co. — 1890
- 13NewsEnglish Galileo' maps on displayChristine McGourty — 14 January 2009
- 14Thomas Harriot's Moon DrawingsAl Van Helden — 1995
- 15Thomas Harriot (1560–1621)Al Van Helden — 1995
- 16BookThomas Hariot, the Mathematician, the Philosopher and the ScholarHenry Stevens — Privately printed at the Chiswick press — 1900
- 17BookSymbols, Impossible Numbers, and Geometric Entanglements: British Algebra Through the Commentaries on Newton's Universal ArithmetickHelena M. Pycior — Cambridge University Press — 1997
- 18JournalHarriot's Maps of the Moon: New InterpretationsStephen Pumfrey — 2009
- 19JournalBorrowed Perceptions: Harriot's Maps of the MoonTerrie F. Bloom — 2016
- 20JournalLunar Maps and Coastal Outlines: Thomas Hariot's Mapping of the MoonAmir Alexander — 1998
- 21JournalMarch 9, 1611: Dutch astronomer Johannes Fabricius observes sunspotsDavid Voss — 2015
- 22JournalSolar Rotation Determined from Thomas Harriot's Sunspot Observations of 1611 to 1613Richard B. Herr — 1978
- 23JournalThomas Harriot on continuous compoundingNorman Biggs — 2013
- 24BookTaming the Unknown: A History of Algebra from Antiquity to the Early Twentieth CenturyVictor J. Katz et al. — Princeton University Press — 2014
- 25BookEuler's gem : the polyhedron formula and the birth of topologyDavid Richeson — Princeton University Press — 2008
- 26BookArtis analyticae praxisThomas Harriot — 1631
- 27BookThomas Harriot's Artis Analyticae Praxis: An English Translation with CommentaryThomas Harriot — Springer — 2007
- 28JournalBefore calculusMatthias Schemmel — September 2010
- 31BookThomas Harriot; Renaissance scientistClarendon Press — 1974
- 32BookA Sourcebook for the Study of Thomas HarriotJohn W. Shirley — Arno Press — 1981
- 33BookThomas Harriot, a BiographyJohn W. Shirley — Clarendon Press — 1983
- 35BookThe Swerve: How the World Became ModernGreenblatt, Stephen — W. W. Norton — 2011