Benjamin Banneker

American mathematician and astronomer

• Born: November 9, 1731
• Birthplace: Baltimore County, Maryland
• Died: October 9, 1806
• Place of death: Baltimore County, Maryland

Banneker’s calculations provided the essential data for almanacs published from 1792 through 1797. A free black in a slave state, Banneker overcame obstacles of rural isolation, little formal education, and racial prejudice to establish himself as a respected scientist, earn a place on the crew that surveyed the District of Columbia, and become a symbol of racial equality in the abolitionist movement. He is also known for his letter to Thomas Jefferson calling on him to end slavery in America.

Early Life

Benjamin Banneker’s American antecedents came in bonds to colonial Maryland. His grandmother, Molly Welsh, was a convict transported from England to Maryland in about 1683. After completing a period of servitude, she became a free landowner in the western part of Baltimore County near the Patapsco River. In 1692, Molly bought two Africans and in a few years restored freedom to both. One of the men, named Bannka, claimed to be the kidnapped son of an African king. In defiance of laws that forbade miscegenation, Molly married the prince and took Banneky as her surname.

The Bannekys had four daughters. The oldest, Mary, born in about 1700, married an African who had been given freedom as a baptismal gift. He had chosen Robert as his Christian name and, when married, took Banneky as his surname. The name’s spelling varied until the mid-eighteenth century, when it settled at Banneker. Three of the four children born to Robert and Mary grew to maturity. The oldest, and the only son, was Benjamin, born in 1731.

In about 1729, Robert bought 25 acres of land close to Molly’s farm. On March 10, 1737, when Benjamin was five years old, Robert purchased 100 acres from the nearby Stout plantation. The title was in Robert’s and Benjamin’s names to ensure that the family could protect its freedom should Robert die suddenly. Maryland laws were not sympathetic to free blacks and authorized reenslavement of those who did not own property.

Banneker’s education was rudimentary. His grandmother taught him to read from the Bible. For a few months, he attended a country school where the schoolteacher, probably a Quaker, taught black and white children. Benjamin learned to write a very clear, even beautiful, script and mastered the fundamentals of mathematics through basic algebra. At some point, he also learned to play the flute and the violin. Though meager, this education powerfully shaped the course of Banneker’s life. He purchased his own Bible in 1763, read it diligently, and sprinkled his writings with scriptural quotations. He never formally joined a Christian denomination, but he often attended Quaker, and sometimes Methodist, services. His reading interests went beyond the Bible to literature in general. He painstakingly compiled a small library, composed essays in his own commonplace book, and wrote poetry.

Mathematics, though, was the subject that most stimulated his intellectual curiosity. He had unusual abilities with numbers. As a young man, he became locally famous for being able to solve fairly complex computations in his head. He had a special fondness for mathematical puzzles and liked to trade tricky problems with his neighbors.

It was probably during such an exchange with a neighbor that Banneker first saw and then borrowed a watch. The timepiece fascinated him, and he dismantled it to observe its moving parts. Using the watch as a model, Banneker produced a clock made entirely of hand-carved hardwoods. The clock kept accurate time, struck the hours, and was the wonder of the Patapsco valley.

Banneker completed the clock in 1753, when he was twenty-two. His father died six years later, leaving Benjamin the sole owner of the Stout acreage. The rest of the property was divided among Benjamin and his two married sisters. Banneker lived with his mother until she died in 1775. He never married and lived the rest of his life on his well-kept, productive farm. He might have died in obscurity had not the Ellicott brothers bought land adjoining the Banneker farm.

Life’s Work

Joseph, Andrew, and John Ellicott brought their large families and the families of several workers to the Patapsco valley in 1771, when Benjamin Banneker was about forty years old. Before they were fully settled, the Ellicotts and their workers bought food from the existing farms. Andrew Ellicott’s young son George developed a special friendship with Banneker. At age fifteen in 1775, George was recognized as a mathematical prodigy, an accomplished surveyor, and a gifted astronomer. With George’s encouragement and assistance, Banneker rapidly mastered advanced mathematics and became fascinated with astronomy. In the fall of 1788, George loaned Banneker books on mathematics and astronomy, a telescope, a set of drafting instruments, a lamp, and a large, oval drop-leaf table.

Banneker soon spent clear nights in open fields observing the heavens. When recording his observations in cold weather he dressed heavily and wrapped himself in blankets. At dawn he returned to his cabin and slept for a few hours. He spent most of the rest of the day at the oval table studying the borrowed books and plotting the movements of the stars. The calculation of a star’s location for a particular date could involve as many as ten different algebraic and logarithmic operations.

As he gained a sure grasp of astronomy, Banneker began the ambitious project of calculating an ephemeris—a table showing the positions of the Earth, Moon, planets, and stars throughout the year. The ephemeris was the basis for projecting eclipses and predicting weather conditions. It was, therefore, the major component of an almanac, a compilation of astronomical and weather-related data for a given year. He was encouraged in this project by his mentor George and by George’s cousin, Major Andrew Ellicott. Major Ellicott had prepared ephemerides for publication from 1781 through 1786, but the demands of his work as surveyor forced him to abandon the time-consuming calculations. In the summer of 1790, Banneker submitted completed ephemerides for 1791 to three publishers, but none of the editors bought his work. Although discouraged, Banneker began an ephemeris for 1792.

In January of 1791, President George Washington instructed Secretary of State Thomas Jefferson to have the District of Columbia surveyed. On February 2, 1791, Jefferson named Major Ellicott the chief surveyor. Ellicott was to find the true meridian and longitude of the future capital and to prepare a topographical map of the ten-square-mile tract of land. Because he was shorthanded, Ellicott turned to Banneker for help. Banneker had no practical experience as a surveyor, but he had mastered the mathematics involved and knew how to work with most of the astronomical instruments.

On February 7, 1791, Banneker, at age fifty-nine, made his first trip outside Baltimore County. During his three-month stay at the site of the future capital, he gained valuable experience as assistant to Ellicott. He learned to use the astronomical clock and other instruments new to him. He also kept a resolution to abstain from drinking wine and hard liquor while working with the surveying crew.

Upon his return home, he finished the ephemeris for 1792. Meanwhile, Joseph and George Ellicott had interested members of the Society of Friends and the antislavery societies in Baltimore and Philadelphia in Banneker. Through their assistance, Banneker’s 1792 ephemeris was published by the Baltimore firm of Goddard and Angell. The almanac, Benjamin Banneker’s Pennsylvania, Delaware, Maryland and Virginia Almanack and Ephemeris for the Year of Our Lord, 1792 was sold in Baltimore, Philadelphia, and Alexandria beginning in December, 1791. The editors of the almanac included a note in the work’s front matter, stating that the almanac was “an extraordinary Effort of Genius—a COMPLETE and ACCURATE EPHEMERIS . . . calculated by a sable Descendant of Africa. . . .” The editors argued that the almanac was proof that skin color had no relationship to mental or intellectual capacity, that all people were alike, and that slavery should be ended. The first four thousand copies quickly sold out, as did a second printing by Goddard and Angell and a condensed edition printed by William Young in Philadelphia.

Banneker prepared an ephemeris that was published in an almanac each year through 1797. The almanacs were extremely popular and sold well. At least twenty-eight editions of these almanacs appeared in those six years. Starting in 1794, Banneker computed tide tables for Chesapeake Bay, a feature that competing almanacs did not contain.

The elderly astronomer was of average height and had a full head of thick, white hair. Though portly, his posture, gentlemanly behavior, and staff gave him a dignified air. Banneker continued to calculate ephemerides through the 1802, the year he turned seventy-one. His capacity for work had diminished, and he was unable to complete the rigorous computations. He died quietly in his home four years later on October 9, 1806.

Significance

Benjamin Banneker’s abilities as a mathematician and astronomer made him famous in his lifetime. There was, however, much more to his fame than his scientific accomplishments themselves. Banneker was the son and grandson of Africans. He was a free black in a predominantly white society that almost universally regarded black people as being mentally inferior to whites. Banneker’s best-known activity—in his lifetime and since—was his correspondence with Thomas Jefferson.

On August 19, 1791, Banneker sent the author of the Declaration of Independence a handwritten copy of his ephemeris and a long letter. He introduced himself as a black man and then eloquently pleaded with Jefferson to use his influence to end the slavery that still kept some of the children of humankind’s one Father from enjoying their “inalienable rights.” Jefferson responded by expressing the hope that people would soon recognize that circumstances, not natural endowments, kept blacks in a condition that suggested inferiority, but he made no pledge to do anything more than to send Banneker’s almanac to abolitionists in France.

Those two letters were printed in the 1793 almanac and reprinted frequently in abolitionist literature in the nineteenth century. Benjamin Banneker had become a symbol of racial equality because he was an example of black achievement. His name has been invoked over the years in black educational efforts, such as Benjamin Banneker College of Prairie View A&M University at Prairie View, Texas.

Bibliography

Allen, Will W., comp. Banneker: The Afro-American Astronomer. Washington, D.C.: Black Heritage Library, 1921. Reprint. Freeport, N.Y.: Books for Libraries Press, 1971. This work is based largely on primary sources. However, the book contains a paper by Daniel Murray that advances the oft-repeated, undocumented claim that Banneker worked with Major Pierre Charles L’Enfant and had a copy of the city’s plans for use after L’Enfant left the capital site in a rage.

Allen, William G. Wheatley, Banneker, and Horton. Boston: D. Laing, 1849. Reprint. Freeport, N.Y.: Books for Libraries Press, 1970. A condensation of an earlier work on records held by the Ellicott family.

Armistead, Wilson. A Tribute for the Negro: Being a Vindication of the Moral, Intellectual, and Religious Capabilities of the Colored Portion of Mankind, with Particular Reference to the African Race. 1848. Reprint. Miami, Fla.: Mnemosyne, 1969. A collection of abolitionist literature. The material on Banneker consists of a brief biographical sketch and a reprint of the Jefferson correspondence.

Baker, Henry E. “Benjamin Banneker, the Negro Mathematician and Astronomer.” Journal of Negro History 3 (April, 1918): 99-118. A fine sketch based upon a rare work prepared by George Ellicott’s daughter Martha Ellicott Tyson.

Bedini, Silvio A. The Life of Benjamin Banneker: The First African-American Man of Science. 2d rev. ed. Baltimore: Maryland Historical Society, 1999. An excellent study of Banneker, based on careful review of secondary materials, previously unused material from private archives, and Banneker’s commonplace book and journal. Originally published in 1971, this expanded edition includes new photographs and information on Banneker’s African roots.

Cerami, Charles. Benjamin Bannecker: Surveyor, Astronomer, Publisher, Patriot. New York: J. Wiley, 2002. A clearly and simply written biography that examines Banneker’s life and the breadth of his career.

Miller, John Chester. The Wolf by the Ears: Thomas Jefferson and Slavery. New York: Free Press, 1977. Miller treats the correspondence between Banneker and Jefferson in the context of Jefferson’s life and slavery in the United States.