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Did You Know? The Sextant Is Much Older Than You Think!

Hey there! Did you know that the sextant has been in use for centuries? Learn more about this fascinating instrument below.

Did You Know? The Sextant Is Much Older Than You Think!

When Was the Sextant Invented?

If you're a sailor or a fan of seafaring adventures, you have probably heard about the sextant. It's an essential navigational tool that's been used for centuries. But do you know when the sextant was invented? Let's dive into the history of navigation to find out!

What is a Sextant?

In simple terms, a sextant is an instrument that helps sailors measure the angle between two objects. By measuring the angle between the horizon and a specific star or planet, sailors can calculate their latitude and longitude and determine their exact location.

Before the sextant was invented, sailors used other tools like the astrolabe, quadrant, and octant to measure the angle of celestial objects. However, these tools had limitations and were not always accurate, especially when the weather conditions were unfavorable.

The sextant revolutionized the art of navigation and became one of the most important inventions in maritime history. Sailors could now determine their location with more precision and avoid dangers like rocks, sandbars, and other hazards.

The Early History of Navigation

Early navigation methods can be traced back to ancient civilizations like the Greeks, Phoenicians, and Chinese. These early sailors used landmarks, natural features like mountains and rivers, and the stars to navigate their vessels. Over time, navigation techniques improved, and sailors developed more sophisticated tools and instruments.

In the early Middle Ages, Arab sailors introduced the astrolabe, a device used to measure the altitude of celestial bodies. The astrolabe was a significant advancement that allowed sailors to determine their latitude and calculate their distance from the equator. In the 15th century, Portuguese navigators developed the quadrant, a tool similar in function to the astrolabe but smaller and more portable. The quadrant was later improved upon by the octant, which had a more precise scale and could measure angles up to 90 degrees.

Creation of the Sextant

The sextant as we know it today was invented by an Englishman named John Hadley in 1731. Hadley had been experimenting with different instruments to find a more accurate way to measure angles. He combined the best features of the octant and the quadrant to create a new tool that was more precise, easier to use, and had a larger range of measurement.

The sextant was quickly adopted by sailors and became widely used in the 18th and 19th centuries. It helped sailors navigate the globe with more accuracy and safety, leading to more successful voyages and discoveries.

Innovations and Modern Alternatives

Over the years, the sextant has undergone various modifications and improvements. For example, in the 19th century, an American engineer named John Moore added mirrors to the sextant, which further enhanced its accuracy and convenience. In the 20th century, electronic navigation systems like GPS replaced the sextant on most modern ships.

Today, the sextant is primarily used in recreational sailing and maritime schools, where sailors and students can learn classic navigation techniques. The instrument remains an icon of maritime history and an enduring symbol of the ingenuity and creativity of sailors and inventors throughout the ages.

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When Was the Sextant Invented?

Navigation has been a crucial tool for humans since ancient times. Early civilizations used landmarks, stars, and celestial bodies to guide their travels across the seas. However, navigating the open water was not always easy, given the many challenges that sailors faced, including unfavorable weather conditions, long journeys, and incorrect maps. As a result, accurate navigation tools became a necessity.

One of the most important navigation tools is the sextant, an instrument used to measure the angle between objects such as the horizon and celestial bodies like the sun, moon, or stars. This measurement allows sailors to calculate their position and plot their course accurately. It's difficult to imagine naval navigation without this invaluable tool, but when was the sextant invented?

Who Invented the Sextant?

John Hadley

John Hadley, an English astronomer and mathematician, is credited with the invention of the sextant in 1730. Hadley was inspired by earlier navigation tools, such as the octant and quadrant, which also measured celestial angles. However, these instruments had limitations that made them less reliable and precise. Hadley's goal was to create a better and more accurate instrument that would assist sailors in their navigation.

Hadley's sextant used two mirrors to reflect the light from the celestial body being measured, allowing the user to observe the celestial object while simultaneously sighting the horizon. This design made the sextant more accurate than previous instruments, leading to its widespread adoption.

Thomas Godfrey

While John Hadley is widely accepted as the inventor of the sextant, some sources credit American inventor Thomas Godfrey with inventing a similar instrument around the same time as Hadley. Godfrey's instrument, the reflecting quadrant, used a similar design and also allowed sailors to measure celestial angles. It's believed that both Hadley and Godfrey independently created similar instruments and were unaware of each other's work.

Other Contributors to Sextant Development

While John Hadley and Thomas Godfrey are the most well-known inventors of the sextant, there were several other inventors and mathematicians who made important contributions to its development. James Ferguson, for example, is credited with improving the accuracy of the sextant and making it smaller and more portable. He also made other major contributions to astronomy and navigation during his lifetime.

Another notable contributor to sextant development is John Bird, an 18th-century English watchmaker who also made important advances in timekeeping. Bird was responsible for creating more robust and durable instruments, including the first sextant to use a Vernier scale for more precise measurements.


The sextant is a crucial instrument that has helped sailors navigate the open seas for centuries. While John Hadley is credited with its invention, other inventors and innovators contributed to its development and advancement. Today, the sextant remains an important tool for naval navigation, even in an age when many sailors rely on modern technology such as GPS. Whether exploring uncharted waters or simply sailing through a storm, the sextant remains a reliable and essential part of any sailor's toolkit.

The sextant is a navigational instrument invented in the early 18th century. It was not until 1757 that John Bird invented an improved version of the sextant which became the basis for the modern instrument. Read more about other navigational inventions in our article on the history of navigation.

When Was the Sextant Invented?

The sextant is an instrument used in navigation that allows sailors and pilots to determine their position accurately. It measures the angular distance between two objects and is widely used in marine navigation. The history of the sextant is interesting and dates back to ancient times.

History of Sextant

The invention of the sextant is usually attributed to an English mathematician named John Hadley. In 1731, John Hadley was given credit for the invention of the octant, which is similar to the sextant. However, the sextant, as we know it today, was not invented until several years later, in the mid-18th century.

The sextant was developed by an English instrument maker named John Bird in 1757. It is believed that John Bird introduced the double-reflected measuring principle that led to the invention of the sextant.

Although John Bird invented the sextant in 1757, it was not until the end of the 18th century that the instrument became widely used in navigation.

How Was the Sextant Used?

The sextant was a major improvement over previous navigation tools. It allowed sailors to measure the angle between two objects, such as the horizon and a star, with greater accuracy. This made it easier to determine a ship's position and navigate the seas.

Navigation by Sea

The sextant played a crucial role in the age of sail, allowing sailors to navigate the open seas with greater precision. The ability to accurately measure the angles between the horizon and celestial objects such as stars and the sun allowed for the calculation of a ship's latitude and longitude, which was invaluable for safe navigation.

The sextant is still widely used in marine navigation, particularly on long voyages where GPS or other electronic navigation systems may not be reliable. It remains a reliable and accurate tool for determining a ship's position on the open seas.


The sextant was also used by astronomers to measure the position of celestial bodies. It provided a way to accurately measure the distance between two astronomical objects, such as the moon and a star. This information was used to calculate the size of the solar system and determine the positions of stars and planets.

Other Applications

The sextant was also used for surveying and mapping, and it played an important role in the development of early cartography. It was a versatile tool that had many applications beyond just navigation.

In conclusion, the sextant is an essential instrument for navigation and has played a vital role in the history of transportation and exploration. Without the sextant, sailors, pilots, and astronomers would not have been able to record their positions and observations with such precision, and the world would be a very different place today.

The Legacy of the Sextant

The sextant is a nautical instrument used to measure the angle between two objects, typically the horizon and a celestial object such as the sun, moon, and stars. It was invented to improve the accuracy of navigation at sea. The sextant is widely regarded as one of the most important innovations in maritime history. Its significance can be seen in the way it revolutionized navigation and influenced the development of other navigation tools. Let's delve deeper into the historical, technological, and cultural impact of this ingenious instrument.

Importance in Maritime History

Before the invention of the sextant, sailors were unable to determine their exact location at sea. They would rely on visual references such as landmarks, shorelines, and the position of the sun and stars. However, these methods were unreliable and often resulted in ships getting lost, running aground, or colliding with other vessels. It was a dangerous time for sea travel, and many lives and cargoes were lost.The sextant, first created in the 1700s, significantly improved navigation accuracy by measuring the angular distance between the horizon and celestial objects. With this information, mariners could calculate their latitude and longitude, which helped them plot their position accurately on a map. This made sea travel safer, more efficient, and paved the way for more ambitious voyages.

Evolution of Navigation Tools

The invention of the sextant was just the beginning of a fascinating journey of innovation in navigation technology. Over the centuries, other navigation tools were developed, building on the principles of the sextant. These included chronometers, compasses, and global positioning systems (GPS).Chronometers were used to measure time accurately, which was essential for calculating longitude. Compasses helped sailors to navigate by indicating magnetic north. GPS systems use signals from satellites to determine precise locations on earth. These advancements in navigation technology were made possible by the sextant and its principles.

Symbolism of the Sextant

The sextant has become a symbol of adventure, exploration, and discovery. It's associated with famous explorers such as Captain James Cook, who used a sextant on his voyages to the Pacific Ocean. The instrument is also linked with modern-day adventurers who use it for celestial navigation. It's a reminder of the important role that navigation and exploration have played in human history.In conclusion, the sextant is a remarkable invention that has left a lasting legacy in maritime history. It improved navigation accuracy, paved the way for other navigation tools, and has become a symbol of adventure and exploration. The impact of the sextant can be seen in the way sea travel has evolved over the centuries. While modern technology has made navigation easier, the sextant remains a testament to the ingenuity of human innovation.

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