Edmund Gunter facts for kids
Edmund Gunter (born 1581 – died 10 December 1626) was an English clergyman, a smart mathematician, a geometer (someone who studies shapes and spaces), and an astronomer (someone who studies stars and planets). He is best known for his important math inventions. These include the Gunter's chain, the Gunter's quadrant, and the Gunter's scale. In 1620, he created the first successful analogue device to help calculate special math problems called logarithmic tangents.
He learned a lot about math from Reverend Henry Briggs. Later, Gunter became a Gresham Professor of Astronomy in 1619 and held this job until he passed away.
About Edmund Gunter
Gunter was born in Hertfordshire, England, in 1581. He went to Westminster School and then to Christ Church, Oxford University in 1599. He became a preacher in 1614 and earned a degree in divinity in 1615. He also became the rector (head priest) of St. George's Church in Southwark.
Throughout his life, Gunter was very interested in how math could be used in the real world. In 1619, a wealthy man named Sir Henry Savile helped create the first two science teaching jobs at Oxford University. Gunter wanted to be the professor of geometry. He showed off his tools like the sector and quadrant, explaining how they could measure stars or distances. Sir Henry Savile thought this was just "showing of tricks" and wasn't proper geometry.
However, a very rich man, the Earl of Bridgewater, supported Gunter. On March 6, 1619, Gunter was chosen to be the professor of astronomy at Gresham College in London. He kept this important job until he died.
Edmund Gunter invented several useful tools. He wrote about them in his books. He created his sector tool around 1606. He first wrote about it in Latin, but it took over sixteen years for him to let the book be published in English. In 1620, he published a math book called Canon triangulorum.
In 1624, Gunter put many of his math works together in one book. It was called The description and use of sector, the cross-staffe, and other instruments for such as are studious of mathematical practise. What was special about this book was that it was written and published in English, not Latin. Gunter said he agreed to publish it in English to help people who didn't understand Latin but still bought his instruments. It was a guide for sailors and surveyors, not just for university scholars.
Gunter was likely the first person to discover (around 1622 or 1625) that a compass needle doesn't always point in exactly the same direction in the same place over time. This is called magnetic declination. At the request of King James I, he published a book in 1624 about the sundials in Whitehall Garden. He also invented the math terms cosine and cotangent. He also suggested to his friend Henry Briggs to use something called the arithmetical complement in math.
His practical inventions are explained below:
Gunter's Chain
Gunter was very interested in geometry, which led him to create a way to measure land using triangles. You could measure distances between points like field corners. Then, using triangles, you could draw the field on a map and figure out its area. He chose a special chain that was 66 feet (20 m) long for this purpose. This chain is now called Gunter's chain.
The length of the chain, 66 feet (20 m), was chosen because it made it easy to calculate land area. For example, an area of 10 square chains is equal to 1 acre. This made it much simpler for surveyors to measure and calculate land sizes.
Gunter's Quadrant
Gunter's quadrant is a tool usually made of wood or brass. It has a special drawing of the sky on it. This tool helps you find the time of day, the sun's direction (azimuth), and other common things related to the sky. You can also use it to measure the height of an object in degrees.
A very rare Gunter quadrant, made by Henry Sutton in 1657, was a useful and powerful tool. It had two small holes for looking through and a string with a weight (plumb line). One side was designed as a Gunter quadrant, and the other side was a trigonometric quadrant. The side with the sky map had lines for hours, a calendar, zodiac signs, star positions, and a vertical dial. The side with the geometric quadrants showed different math functions, rules, a shadow quadrant, and a line for chords.
Gunter's Scale
Gunter's scale, also known as Gunter's rule, was often called the "Gunter" by sailors. It is a long, flat ruler, usually 2 feet (610 mm) long and about 1½ inches (40 mm) wide. It has many different scales or lines drawn on it. One side has natural math lines (like lines for chords, sines, tangents, and rhumbs). The other side has special logarithmic lines.
Sailors used this tool with a pair of compasses to solve problems in navigation and trigonometry. It was an early version of the slide rule, which was a calculating tool used from the 1600s until the 1970s.
Gunter's line, or line of numbers, refers to the special scale on the ruler that uses logarithms. This is like the scales used on slide rules for multiplying and dividing numbers.
Gunter Rig
A type of sail on a boat that looks like a gaff rig, but with the top pole (gaff) standing almost straight up, is called a Gunter rig. It's also known as a "sliding gunter" because it looks a bit like Gunter's rule.
See also
- Gresham Professor of Astronomy
- History of geomagnetism
