Benjamin Banneker: Astronomer, Surveyor, Scientist, Writer

Benjamin Banneker (1731-1806), a free Black man and a contemporary of the Founding Fathers, was an interdisciplinary pioneer who taught himself about various forms of science, astronomy, and geographical surveying. His greatest contribution was his series of widely published almanacs that measured precise astronomical calculations, tides, and weather predictions. In the late 1700s, this scientific data was highly valued by farmers and sailors whose lives depended on this information.

Just as Benjamin Franklin added pithy sayings to his almanacs (Poor Richard’s Almanack), Banneker determined the message he wanted to share was about the importance of racial equality. He had enough confidence that he also spoke truth to power. In 1791, he wanted to send a copy of his first almanac to government leader Thomas Jefferson. Banneker felt the almanac would be of interest, and with his cover letter, he could address the fact that the author of the Declaration of Independence should re-think his position as a slaveholder. It was a brave move to make.

Why do we hear little or nothing about Banneker? Likely because in the 1790s it was highly inconvenient to bring awareness to a free Black man who was clearly quite intelligent. As the Founding Fathers worked on the United States Constitution, they received support from the Southerners representing the slave-holding states by offering that slaves would be valued as only 3/5 of a person. 

If Banneker and other Black men were treated as equal to whites, people might question how the country’s system was established.

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Banneker’s Early Life

Benjamin Banneker was descended from a white grandmother and an African slave. His grandmother arrived in this country from England to fulfill a term as an indentured servant. When her time of service was over, she was released and given some “starter” money. The young woman continued to save and purchased farmland outside Baltimore, and she acquired two slaves to work the land for her. She soon fell in love and married the slave known as Bannaka.  In 1731, their daughter gave birth to the man we know as Benjamin Banneker while still living on the family farm.

The extended family lived on the grandmother’s farm and successfully worked the land.  The family members were among only 200 free Blacks in the county, out of a population of 13,000 whites and 4,000 slaves.

The farm expanded and was quite successful. Biographer Charles Cerami in his book, Benjamin Banneker: Surveyor, Astronomer, Publisher, Patriot, attributes this knowledge to Benjamin’s grandfather (the former slave). He was brought to the colonies from the Republic of Mali in western Africa and was part of the Dogon tribe. These people were thought to have an advanced understanding of several aspects of farming including the importance of planting times, irrigation, and the need to rotate crops. Crop rotation was a particularly early concept for that time.

Education

Benjamin’s grandmother taught Benjamin to read and write. After that, he was almost fully self-taught. Their farm was near a Quaker community, and Quakers were more open-minded than most colonists. When Peter Heinrichs, a Quaker teacher, started a one-room school, he welcomed Banneker as one of his students.

After only a year or so, Banneker had to return to working  on the farm, but Heinrichs remained in touch. He loaned books from his library to the teenager, and the two enjoyed talking about what Benjamin was reading. With this support, Banneker was able to continue to educate himself in history, science, astronomy, and literature.

Banneker Learned to Build a Clock

Among Banneker’s early accomplishments was the construction of an intricately made wooden clock. While there were other clockmakers working in the colonies, Banneker’s clock is notable because it was hand-carved and Banneker was totally self-taught.

In 1753 when Banneker was 22, a pocket watch had been left with him for safekeeping by a friend who was going on a journey. Banneker was fascinated by the instrument and took it apart to better understand how the pocket watch worked.

He carefully sketched the components of the watch, noting how each gear had to coordinate with the interlocking one.  He then proceeded to carve a larger version of each piece out of wood. In this manner, he successfully built his own wooden clock. It reportedly kept accurate time and struck the hour for the remainder of Benjamin’s life—over 50 years.

Of course, he also reassembled the pocket watch in preparation for the owner’s return.

Ellicott Family Became Neighbors

In the early 1770s, Quaker brothers Joseph, Andrew, and John Ellicott moved from Bucks County to Maryland where they found affordable land and a strong river (the Patapsco) offering excellent water power.  The family ran flour mills in Bucks County, and the three brothers envisioned establishing a new base for their business and building a new community.

The farmland in the area was also ready for a refresh. Tobacco was a primary crop and the soil was depleted. The Ellicotts urger the local farmers to switch to wheat that they could then mill for them. Business boomed for Ellicotts as well as the farmers. The town became known as Ellicott City. 

Benjamin Banneker’s family also switched to planting wheat, and he Ellicotts were happy to become acquainted with Benjamin Banneker. As Quakers they were welcoming to people of all races, and soon Banneker began borrowing books from them. As the next generation of Ellicotts took over the business, the families continued to work together.

Major Andrew Ellicott (1754–1820) and George Ellicott (1760-1832) were part of the younger generation. George loaned Banneker a telescope, celestial globes, and mathematical texts, sparking Banneker’s work in formal astronomy.

Andrew became one of the nation’s premier geographers and surveyors. He was appointed by George Washington to lead the 1791 boundary survey for Washington, D.C. Andrew hired Banneker to help with the surveying of what was considered the Federal City.

Surveying the Federal City

By George Washington’s choice, the land for the federal city lay along the Potomac River, taking sections from Maryland and Virginia. It was not going to be an easy job as the area was swampy and overgrown. Surveyors had to hack their way through brush and ford streams to mark off the specified area of 10 square miles (16 km).  

Banneker learned the basics of surveying by reading a book “Gibson’s Treatise on Practical Surveying,” but his value to Andrew Ellicott was as a scientist who understood the movement of the heavens.  Before modern surveying tools existed, surveyors turned to astronomers for information on star movements. Based on the celestial movements, they could then calculate land distances. For the Federal City, Banneker’s main job was taking astronomical readings to establish the survey’s starting point and maintain a precision clock to sync ground coordinates with the night sky.

After spending the first several months with the team—the time when the measurements were crucial–Banneker became concerned about his farm. He was 59 and never married, so he was managing the land himself. He determined he needed to go home.

Some experts denigrate Banneker’s contribution to the surveying project. However, given his helpful scientific knowledge and the long-term friendship with the Ellicotts, there is no evidence that indicates he was anything but a full team member.

The Importance of Almanacs

When we hear about Benjamin Franklin’s Poor Richard’s Almanack, we generally think of the pithy sayings that Franklin included in his book. 

But the true value of an almanac to the people of the late 1700s and early 1800s was the calendar providing important dates and the expected weather, based on astronomical and astrological calculations. For communities near the sea, the timing of the tide levels was vital information. Sailors needed to know in preparation for trips, and expected rainfall was helpful to farmers in the area. Almanacs also provided important governmental dates—elections as well as circuit court schedules for the area.  An almanac was often the only book owned by a family.

Banneker’s Almanac

When Benjamin Banneker left the surveying job, he settled in at home and began preparing material for an almanac. The Ellicotts connected him with publishers.  

The first edition was published in 1792, and its full title was descriptive of the content: “Pennsylvania, Delaware, Maryland, and Virginia Almanack and the Motions of the Sun and Moon,… “  The title goes on to note that it gives timing of the rising and setting of the sun, eclipses, judgment of the weather, dates of festivals and other remarkable days, days for holding the Supreme Court and circuit courts in the area in addition to “useful Tables and valuable receipts.”

Asked for Review

David Rittenhouse, a renowned mathematician, astronomer, and surveyor in Philadelphia, was sent a copy of Banneker’s almanac for an initial read.  He wrote back that the papers reflected “a very extraordinary performance considering the colour of the Author.”

Charles Cerami’s biography notes Banneker’s reply: “I am annoyed to find that the subject of my race is so much stressed. The work is either correct or it is not. In this case, I believe it to be perfect.”

Letter to Thomas Jefferson

Prior to the publication of the first edition, Banneker decided to send a pre-publication manuscript of the almanac to Thomas Jefferson.  Banneker knew that the correctness of his ephemeris (the celestial readings) would speak volumes to Thomas Jefferson, now serving as Secretary of State, who himself had a deep knowledge of the subject.

Over the course of two weeks, Banneker drafted and re-drafted his cover letter to Jefferson, thinking carefully about what he was going to say and how he would phrase it.

This was a time when Blacks were considered “lesser than.”  Many were slaves and those that were free were not permitted to be heard as witnesses in court. The audacity of a Black man, albeit a free Black man, writing to such an important man as Jefferson would have been viewed as out of place.

Banneker was well aware that Thomas Jefferson’s view of “all men are created equal” did not extend to full equality for Black people, and Banneker wanted to politely make a point about this.

His letter contained a plea for justice for African Americans, and Banneker noted the contradiction of what Jefferson wrote about equality for all was countered by the “groaning captivity and cruel oppression” Jefferson used on “so numerous a part of my [Banneker’s] brethren.” (To read the letter in full, click here.)

Jefferson’s Response

Thomas Jefferson acknowledged the receipt of the letter and the almanac. He did not respond directly to Banneker’s condemnation of him as a slave owner, but he did thank him for the almanac and noted that “no body wishes more than I do to see such proofs as you exhibit that nature has given to our black brethren, talents equal to those of the other colours of men.”

Jefferson’s letter noted that he sent the manuscript on to the Secretary of the Academy of Science in Paris to demonstrate the “ability of men of Banneker’s colour.”  There is no record of it having been received at the Academy, however, Jefferson sent a manuscript—possibly the manuscript Banneker sent him—to a noted French mathematician and abolitionist. Jefferson’s letter touted the fact that “we have now in the United States, a negro, the son of a black man born in Africa, and a black woman born in the United States…” working to survey the federal city.  Jefferson makes claim that he himself thought of hiring Banneker for the job.

But after Banneker’s death, Jefferson told another story.  In 1809, Jefferson wrote a letter indicating suspicion that Ellicott helped greatly with the ephemeris; Jefferson noted that he felt Banneker to have a “mind of very common stature.” 

Jefferson may have failed to take into account the full picture. Creating an almanac is a very tedious job involving lots of scientific study and mathematical calculation. The Ellicotts were busy with their own businesses. Many would say that the Ellicotts provided tools and advocacy while Banneker provided intellectual labor and mathematical precision.

The Success of the Almanac

With the support of the Ellicott family as well as the Society for the Promotion of the Abolition of Slavery in Maryland and Pennsylvania, the first almanac achieved commercial success.

Banneker went on to write and publish annual editions for the next six years.  The publisher’s forward noted with praise the accomplishment of one of “Afric’s sons.”

Mixed in with the scientific were philosophical comments, essays in prose and verse, farming advice, and Banneker’s continued reminder that America should be embarking on a time of racial equality.

Banneker Astronomical Predictions

Banneker’s study of the night sky led him to the concept that distant stars might represent separate solar systems.  This was at a time when there were no telescopes to confirm such a theory, and though a little-known Englishman, Thomas Wright, had written about the idea, it was not a topic that was widely discussed nor was his book well-disseminated. 

Other great thinkers like Copernicus and Galileo had never envisioned what lay beyond our solar system. Yet Benjamin Banneker envisioned it.

End of Life

By 1797, sales of his almanac were slowing, and Banneker was not in great health. (Several sources noted that he was a heavy drinker.)  The farm had become a lot for him to manage alone, so he gave much of his land to the Ellicotts in return for an annuity.

As he achieved a level of fame, some people came as tourists to visit Benjamin Banneker.  But there were others who were uncomfortable with a learned Black man.  Banneker received threats against his life.  Occasionally he would be reading in his cabin at night, and someone would come by and take shots at his cabin.

Benjamin Banneker died in 1806.

On the day of his funeral, the cabin, filled with notebooks recording thoughts of a lifetime, was torched and burned to the ground.  It is hard to think this was accidental.

With the fire, Americans lost priceless documents that would have done so much to further explain the thought process and scientific knowledge of this self-taught genius.  His wooden clock which had also continued to function flawlessly was also lost in the fire.

The information scholars rely on today to better understand Banneker’s level of knowledge is Banneker’s published almanacs, as well as a few of his notebooks which he had loaned to the Ellicotts.  These were spared from the fire.

By pulling together the numerous pieces of Benjamin Banneker’s life, it is very clear that he was an extraordinary man who deserved much more recognition than he has received.

Frequently Asked Questions about Benjamin Banneker

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