The term "computer", in use from the early 17th century (the first known written reference dates from 1613), meant "one who computes": a person performing mathematical
calculations, before
electronic calculators became available.
Alan Turing
Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher and theoretical biologist. He was highly influential in the development of theoretical computer ...
described the "human computer" as someone who is "supposed to be following fixed rules; he has no authority to deviate from them in any detail." Teams of people, often women from the late nineteenth century onwards, were used to undertake long and often tedious calculations; the work was divided so that this could be done in parallel. The same calculations were frequently performed independently by separate teams to check the correctness of the results.
Since the end of the 20th century, the term "human computer" has also been applied to individuals with prodigious powers of
mental arithmetic, also known as
mental calculators.
Origins in sciences
Astronomer
An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...
s in
Renaissance
The Renaissance ( , ) is a Periodization, period of history and a European cultural movement covering the 15th and 16th centuries. It marked the transition from the Middle Ages to modernity and was characterized by an effort to revive and sur ...
times used that term about as often as they called themselves "
mathematicians" for their principal work of calculating the
positions of planets. They often hired a "computer" to assist them. For some people, such as
Johannes Kepler
Johannes Kepler (27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, Natural philosophy, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best know ...
, assisting a scientist in computation was a temporary position until they moved on to greater advancements. Before he died in 1617,
John Napier
John Napier of Merchiston ( ; Latinisation of names, Latinized as Ioannes Neper; 1 February 1550 – 4 April 1617), nicknamed Marvellous Merchiston, was a Scottish landowner known as a mathematician, physicist, and astronomer. He was the 8 ...
suggested ways by which "the learned, who perchance may have plenty of pupils and computers" might construct an improved
logarithm table.
Computing became more organized when the Frenchman
Alexis Claude Clairaut (1713–1765) divided the computation to determine the time of the return of
Halley's Comet
Halley's Comet is the only known List of periodic comets, short-period comet that is consistently visible to the naked eye from Earth, appearing every 72–80 years, though with the majority of recorded apparitions (25 of 30) occurring after ...
with two colleagues,
Jérôme Lalande
Joseph Jérôme Lefrançois de Lalande (; 11 July 1732 – 4April 1807) was a French astronomer, freemason and writer. He is known for having estimated a precise value of the astronomical unit (the distance from the Earth to the Sun) using measu ...
and
Nicole-Reine Lepaute. Human computers continued plotting the future movements of astronomical objects to create celestial tables for
almanacs in the late 1760s.
The computers working on the ''
Nautical Almanac'' for the British Admiralty included
William Wales,
Israel Lyons and
Richard Dunthorne. The project was overseen by
Nevil Maskelyne. Maskelyne would borrow tables from other sources as often as he could in order to reduce the number of calculations his team of computers had to make. Women were generally excluded, with some exceptions such as
Mary Edwards who worked from the 1780s to 1815 as one of thirty-five computers for the British ''Nautical Almanac'' used for navigation at sea. The United States also worked on their own version of a nautical almanac in the 1840s, with
Maria Mitchell being one of the best-known computers on the staff.
Other innovations in human computing included the work done by a group of boys who worked in the Octagon Room of the
Royal Greenwich Observatory for Astronomer Royal
George Airy. Airy's computers, hired after 1835, could be as young as fifteen, and they were working on a backlog of astronomical data. The way that Airy organized the Octagon Room with a manager, pre-printed computing forms, and standardized methods of calculating and checking results (similar to the way the ''Nautical Almanac'' computers operated) would remain a standard for computing operations for the next 80 years.
Women were increasingly involved in computing after 1865. Private companies hired them for computing and to manage office staff.
In the 1870s, the United States
Signal Corps
A signal corps is a military branch, responsible for military communications (''signals''). Many countries maintain a signal corps, which is typically subordinate to a country's army.
Military communication usually consists of radio, telephone, ...
created a new way of organizing human computing to track weather patterns. This built on previous work from the
US Navy
The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...
and the
Smithsonian meteorological project. The Signal Corps used a small computing staff that processed data that had to be collected quickly and finished in "intensive two-hour shifts". Each individual human computer was responsible for only part of the data.
In the late nineteenth century
Edward Charles Pickering organized the "
Harvard Computers". The first woman to approach them,
Anna Winlock, asked
Harvard Observatory for a computing job in 1875. By 1880, all of the computers working at the Harvard Observatory were women. The standard computer pay started at twenty-five cents an hour. There would be such a huge demand to work there, that some women offered to work for the Harvard Computers for free. Many of the women astronomers from this era were computers with possibly the best-known being
Florence Cushman,
Henrietta Swan Leavitt, and
Annie Jump Cannon, who worked with Pickering from 1888, 1893, and 1896 respectively. Cannon could classify stars at a rate of three per minute.
Mina Fleming, one of the Harvard Computers, published ''The Draper Catalogue of Stellar Spectra'' in 1890. The catalogue organized stars by
spectral lines. The catalogue continued to be expanded by the Harvard Computers and added new stars in successive volumes.
Elizabeth Williams was involved in calculations in the search for a new planet,
Pluto
Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...
, at the
Lowell Observatory.
In 1893,
Francis Galton
Sir Francis Galton (; 16 February 1822 – 17 January 1911) was an English polymath and the originator of eugenics during the Victorian era; his ideas later became the basis of behavioural genetics.
Galton produced over 340 papers and b ...
created the Committee for Conducting Statistical Inquiries into the Measurable Characteristics of Plants and Animals which reported to the
Royal Society
The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
. The committee used advanced techniques for scientific research and supported the work of several scientists.
W.F. Raphael Weldon, the first scientist supported by the committee worked with his wife, Florence Tebb Weldon, who was his computer. Weldon used logarithms and mathematical tables created by
August Leopold Crelle and had no calculating machine.
Karl Pearson
Karl Pearson (; born Carl Pearson; 27 March 1857 – 27 April 1936) was an English biostatistician and mathematician. He has been credited with establishing the discipline of mathematical statistics. He founded the world's first university ...
, who had a lab at the
University of London
The University of London (UoL; abbreviated as Lond or more rarely Londin in Post-nominal letters, post-nominals) is a collegiate university, federal Public university, public research university located in London, England, United Kingdom. The ...
, felt that the work Weldon did was "hampered by the committee". However, Pearson did create a mathematical formula that the committee was able to use for data correlation. Pearson brought his correlation formula to his own Biometrics Laboratory. Pearson had volunteer and salaried computers who were both men and women.
Alice Lee was one of his salaried computers who worked with
histogram
A histogram is a visual representation of the frequency distribution, distribution of quantitative data. To construct a histogram, the first step is to Data binning, "bin" (or "bucket") the range of values— divide the entire range of values in ...
s and the
chi-squared statistics. Pearson also worked with
Beatrice and
Frances Cave-Brown-Cave. Pearson's lab, by 1906, had mastered the art of
mathematical table making.
Mathematical tables
Human computers were used to compile 18th and 19th century Western European
mathematical tables, for example those for
trigonometry
Trigonometry () is a branch of mathematics concerned with relationships between angles and side lengths of triangles. In particular, the trigonometric functions relate the angles of a right triangle with ratios of its side lengths. The fiel ...
and
logarithm
In mathematics, the logarithm of a number is the exponent by which another fixed value, the base, must be raised to produce that number. For example, the logarithm of to base is , because is to the rd power: . More generally, if , the ...
s. Although these tables were most often known by the names of the principal
mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...
involved in the project, such tables were often in fact the work of an army of unknown and unsung computers. Ever more accurate tables to a high degree of precision were needed for navigation and engineering. Approaches differed, but one was to break up the project into a form of
piece work completed at home. The computers, often educated middle-class women whom society deemed it unseemly to engage in the professions or go out to work, would receive and send back packets of calculations by post. The Royal Astronomical Society eventually gave space to a new committee, the Mathematical Tables Committee, which was the only professional organization for human computers in 1925.
Fluid dynamics
Human computers were used to predict the effects of building the
Afsluitdijk
The Afsluitdijk (; ; "closure dyke") is a major dam and causeway in the Netherlands. It was constructed between 1927 and 1932 and runs from Den Oever in North Holland province to the village of Zurich, Friesland, Zurich in Friesland province, o ...
between 1927 and 1932 in the
Zuiderzee in the
Netherlands
, Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...
. The computer simulation was set up by
Hendrik Lorentz.
A visionary application to meteorology can be found in the scientific work of
Lewis Fry Richardson
Lewis Fry Richardson, Fellow of the Royal Society, FRS (11 October 1881 – 30 September 1953) was an English mathematician, physicist, meteorologist, psychologist, and Pacifism, pacifist who pioneered modern mathematical techniques of weather ...
who, in 1922, estimated that 64,000 humans could forecast the weather for the whole globe by solving the attending differential
primitive equations
The primitive equations are a set of nonlinear partial differential equations that are used to approximate global atmosphere, atmospheric flow and are used in most Global climate model, atmospheric models. They consist of three main sets of balance ...
numerically. Around 1910 he had already used human computers to calculate the stresses inside a masonry dam.
Wartime computing and electronics
It was not until
World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
that computing became a profession. "The First World War required large numbers of human computers. Computers on both sides of the war produced map grids, surveying aids, navigation tables and artillery tables. With the men at war, most of these new computers were women and many were college educated."
This would happen again during
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
, as more men joined the fight, college educated women were left to fill their positions. One of the first female computers, Elizabeth Webb Wilson, was hired by the Army in 1918 and was a graduate of
George Washington University
The George Washington University (GW or GWU) is a Private university, private University charter#Federal, federally-chartered research university in Washington, D.C., United States. Originally named Columbian College, it was chartered in 1821 by ...
. Wilson "patiently sought a war job that would make use of her mathematical skill. In later years, she would claim that the war spared her from the 'Washington social whirl', the rounds of society events that should have procured for her a husband"
and instead she was able to have a career. After the war, Wilson continued with a career in mathematics and became an
actuary
An actuary is a professional with advanced mathematical skills who deals with the measurement and management of risk and uncertainty. These risks can affect both sides of the balance sheet and require investment management, asset management, ...
and turned her focus to
life tables.
Human computers played integral roles in the World War II war effort in the United States, and because of the depletion of the male labor force due to the
draft
Draft, the draft, or draught may refer to:
Watercraft dimensions
* Draft (hull), the distance from waterline to keel of a vessel
* Draft (sail), degree of curvature in a sail
* Air draft, distance from waterline to the highest point on a v ...
, many computers during World War II were women, frequently with degrees in mathematics. In the 1940s, women were hired to examine nuclear and particle tracks left on photographic emulsions. In the
Manhattan Project, human computers working with a variety of mechanical aids assisted numerical studies of the complex formulas related to
nuclear fission
Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactiv ...
.
Human computers were involved in calculating ballistics tables during World War I. Between the two world wars, computers were used in the Department of Agriculture in the United States and also at
Iowa State College. The human computers in these places also used calculating machines and early electrical computers to aid in their work. In the 1930s, The Columbia University Statistical Bureau was created by
Benjamin Wood. Organized computing was also established at
Indiana University, the
Cowles Commission and the
National Research Council.
Following World War II, the
National Advisory Committee for Aeronautics
The National Advisory Committee for Aeronautics (NACA) was a United States federal agency that was founded on March 3, 1915, to undertake, promote, and institutionalize aeronautical research. On October 1, 1958, the agency was dissolved and its ...
(NACA) used human computers in flight research to transcribe raw data from celluloid film and
oscillograph paper and then, using
slide rules and electric
calculator
An electronic calculator is typically a portable electronic device used to perform calculations, ranging from basic arithmetic to complex mathematics.
The first solid-state electronic calculator was created in the early 1960s. Pocket-si ...
s, reduced the data to standard engineering units.
Margot Lee Shetterly's biographical book, ''
Hidden Figures'' (made into a
movie of the same name in 2016), depicts African-American women who served as human computers at
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...
in support of the
Friendship 7, the first American crewed mission into Earth orbit.
NACA had begun hiring black women as computers from 1940. One such computer was
Dorothy Vaughan who began her work in 1943 with the
Langley Research Center as a special hire to aid the war effort,
and who came to supervise the
West Area Computers, a group of African-American women who worked as computers at Langley. Human computing was, at the time, considered menial work. On November 8, 2019, the
Congressional Gold Medal
The Congressional Gold Medal is the oldest and highest civilian award in the United States, alongside the Presidential Medal of Freedom. It is bestowed by vote of the United States Congress, signed into law by the president. The Gold Medal exp ...
was awarded "In recognition of all the women who served as computers, mathematicians, and engineers at the National Advisory Committee for Aeronautics and the National Aeronautics and Space Administration (NASA) between the 1930s and the 1970s."

As electrical computers became more available, human computers, especially women, were drafted as some of the first
computer programmers. Because the six people responsible for setting up problems on the
ENIAC
ENIAC (; Electronic Numerical Integrator and Computer) was the first Computer programming, programmable, Electronics, electronic, general-purpose digital computer, completed in 1945. Other computers had some of these features, but ENIAC was ...
(the first general-purpose electronic digital computer built at the
University of Pennsylvania
The University of Pennsylvania (Penn or UPenn) is a Private university, private Ivy League research university in Philadelphia, Pennsylvania, United States. One of nine colonial colleges, it was chartered in 1755 through the efforts of f ...
during World War II) were drafted from a corps of human computers, the world's first professional computer programmers were women, namely:
Kay McNulty,
Betty Snyder,
Marlyn Wescoff,
Ruth Lichterman,
Betty Jean Jennings, and
Fran Bilas.
[ENIAC Programmers Project – Awards](_blank)
Human-assisted computation
The term "human computer" has been recently used by a group of researchers who refer to their work as "human computation". In this usage, "human computer" refers to activities of humans in the context of
human-based computation (HBC).
This use of "human computer" is debatable for the following reason: HBC is a computational technique where a machine outsources certain parts of a task to humans to perform, which are not necessarily algorithmic. In fact, in the context of HBC most of the time humans are not provided with a sequence of exact steps to be executed to yield the desired result; HBC is agnostic about how humans solve the problem. This is why "outsourcing" is the term used in the definition above. The use of humans in the historical role of "human computers" for
HBC is very rare.
See also
*
Difference enginean early automatic mechanical calculator designed to replace human computers
*
List of obsolete occupations
*
Mathematical Tables Projecta project of the
Works Progress Administration
The Works Progress Administration (WPA; from 1935 to 1939, then known as the Work Projects Administration from 1939 to 1943) was an American New Deal agency that employed millions of jobseekers (mostly men who were not formally educated) to car ...
(WPA) that employed human computers
*
Mentatfictional human computers in the
''Dune'' universe
*
Women in computing
Women in computing were among the first programmers in the early 20th century, and contributed substantially to the industry. As technology and practices altered, the role of women as programmers has changed, and the recorded history of the fi ...
Notes
References
*
*
*
* Grier, David Alan (May 11, 2001).
The Human Computer and the Birth of the Information Age', Joseph Henry Lecture,
Philosophical Society of Washington.
*
*
Excerpt
*
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*
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*
External links
photograph, October 1949.
, by David Skinner
{{DEFAULTSORT:Computer (job description)
Computer occupations
History of computing
Classes of computers
Obsolete occupations