Science Saturday-by Charlie Keeble

Autistic Conservative Charlie Keeble is also a passionate science geek and likes to read about scientific discoveries and technological innovations. Taking a break from politics he brings this special series called Saturday Science to the Havering Daily to tell the story of famous scientists and inventors from Essex.

William Gilbert: Magnetic Terra

William Gilbert was the first ever experimental scientist and changed the way we explore the natural phenomena of Earth. He was born in 1544 in Colchester and attended St John’s College, Cambridge where he gained a medical degree and practiced as a physician. During his education and throughout his life he rejected the old fashioned Aristotelian method of teaching and understanding nature. This is a form of studying science and nature using a combination of observation and reasoning, as developed by Aristotle in ancient Greece. Gilbert believed that his methods were incapable of making logical deductions in the way nature behaved because he didn’t prove it by experiment using physical objects to demonstrate the way that natural objects moved and behaved the way they did. 

What Gilbert set out to do was to prove that if it can be replicated by constructed devices used by human hands  then that could be used to show how nature behaves in a certain way. Gilbert made the subject of his experimental science magnetism and in doing so he proved that the Earth was magnetic. I read about his science and all of his studies on magnets in his book called The Magnet, which was published in 1600. In it he showed that he used a magnetic model of the Earth called a terrella made out of a magnetic material called lodestone. This was the principle tool for which he did all his experiments with magnetism.

I first read The Magnet in 2014 and kept my own copy for research purposes for an incomplete book that I was planning to celebrate famous scientists from Essex. Gilbert’s science covers all of the basics commonly known today in the field of physics and electromagnetism. Such as how unlike poles of a magnet are attracted to one another, and that the larger the magnet the stronger the force of attraction to iron will be. 

Before Gilbert came along sailors using compasses were not sure about the cause of why their needles pointed in a northly direction. It was believed that they were attracted to the north star of Polaris, or that there was a large magnetic island on the north pole. But Gilbert used his lodestone terrella to argue that the Earth itself was magnetic because it had an iron core. This is now common knowledge in geology and he was the first man to recognise it. The Earth’s magnetic field is generated by the hot metal liquid outer core constantly travelling around the solid inner core at around a thousand miles per hour. This spinning ocean of iron at the centre of the Earth generates an electric field that extends out towards the poles and around the Earth. The same principle of this magnetic field also applies to how electric dynamos work that generate electricity for our homes.

He also saw how the shape of the magnetic metal’s body affected the direction and order of the magnetic field lines travelling through it’s body by making lodestones of different shapes. Imagine a lodestone as your hand (as shown in the pictures here), here the field lines (which I’ve drawn in as arrows) travel to the norths of your fingers and then round to the back of your hand and where your thumb is that creates an asymmetrical direction and order on the eastern side of your palm. You close your fist and the polarity of the field lines change so they run through your fist, up your knuckles where your thumb is and then travel to where your little finger is. Remarkably the direction of the Earth’s magnetic field isn’t constant neither, as it has shifted it’s direction and flipped from different geographical parts of the Earth over the last 700 million years. There was a number of times in Earth’s history when your compass would point south or north west, depending on which way magnetic north flipped.

Gilbert carried out many experiments to explain the magnetic properties of the Earth including scattering pieces of iron on the terrella to show the direction of the magnetic field. Thus proving that the Earth’s magnetism behaved as a field that stretched outwards and circulated around the planet travelling from north to south and back again. Among other discoveries in his laboratory study he developed the first electrical measuring instrument called the electroscope. This detects the presence of electrical charge on a body. 

In his book Gilbert also made studies of static electricity. He coined the term electricus meaning “like amber”, where in his words it meant “like amber in it’s attractive properties”. The Greek word for amber is electron. Now amber is a fossilized tree resin with a distinct yellow-gold colour, and it has electrical properties which made it applicable to studies in magnetism. This property of static electricity is why amberwas also used historically in ancient medicine. When amber is rubbed it generates a charge that attracts itself to light substances. This explains the friction between two different charges of objects (one positive and one negative) producing electric charge and hence he discovered that materials had electrical charge, which led to the discovery of electricity in the industrial revolution. 

As well as experimental science Gilbert was also a physician to Queen Elizabeth 1st and was present at her bedside until the day she died. Coincidently Gilbert passed away in the same year she departed in 1603, from the bubonic plague. His legacy continues to live onto this day. There is a scientific measurement named in his honour, that is now called the magnetic potential and there is a school in Colchester named for him. He is buried in Holy Trinity Church, Colchester. 

It’s amazing how a scientist in the 16th century was able to discover the remarkable properties of natural phenomena that affected people’s lives using such primitive technology. The way William Gilbert conducted his scientific studies would be crucial to many other scientists in the future to prove their own theories about matter and materials. It’s now widely established in the scientific world that for a theory to be proven it must be done using experiment and observation, andthe results of that to be used to draw a logical conclusion. Later Gilbert’s science would be crucial to the development of electrical energy and that electricity and magnetism were the same aspects of a single force: electromagnetism.